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### Course: 7th grade (Illustrative Mathematics)>Unit 6

Lesson 9: Lesson 17: Modeling with inequalities

# Two-step inequality word problem: R&B

Let's tackle this word problem together. We'll interpret the information and then construct a linear inequality to solve it. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• White Fang posted a similar question dated two years ago, but the answer isn't what I am looking for.

How will I know whether or not it is `>=`, `<=`, `<` or just `>`? That is where I keep getting my answers wrong when I am doing the practice pages and I can't seem to place my finger on what's going on.

Thanks to anyone who helps!
(12 votes)
• When I learned this at school, my teacher told the class some key phrases to look for to determine which sign to use. For >=, some are "is at least" and "is no less than" (x>=5; x is at least 5). <= would be "no more than", "at most", or "up to" (x<=5; x is at most 5). < is "lower than", "fewer than" (x<5; x is fewer or less than 5). > is "greater than", "exceeds", and "more than" (x>5; x is greater than or exceeds 5). When determining what to use in a word problem, look for those phrases or look at each sign and see what makes the most sense for the situation based on those phrases. Hope this helps - comment with any questions you have!
(18 votes)
• Have a problem with a question in "Interpreting and solving linear Inequalities" The question is:
"Kim's softball team is playing in the championship game. They are losing by a score of 17 to 6. There are 4 innings to go. Kim wants to know how many runs her team needs per inning to win the game if the other team does not score."
I don't know this game and I thought it's not important to answer the question, but it seems I'am wrong with that. I thought they need 12 points more to win (17-6+1), so they have to do 3 runs in every inning (whatever this is). I get it wrong, like I said. The first sentence in the hints is: "Kim's team already has 6 runs." I don't get it. Where in the question is the information, that they have 6 runs. I thought the 6 means the points they have. I need a hint I understand.
(7 votes)
• Run does mean points. However, the equation is 6+4p>17. (let p = points) Which would mean that 4p>11. And p would equal 11/4 points per inning, Round it up I made the mistake of rounding it down and got the question wrong.
(4 votes)
• The ones in the exercise are a lot more difficult. The wording really throws everything off.
(8 votes)
• These videos, although informative, don't really help me or, as I can see, many people with the following quiz. It's been the same case a lot of times: the videos explain the solution to an easy problem, then you get blown away by the more dramatically complicated questions in the quiz.
(8 votes)
• I don't know what you mean, sorry. You can try and learn more by watching the videos multiple times and doing the quiz multiple times.
(0 votes)
• I wish he gave some harder examples. I feel like this video is easier than the exercise.
(7 votes)
• My solution was: L≥120000-(45000+33000) which seems fine.
But I encountered a similar problem where my approach fails.
My solution: p ≥ (620 - 450) / 37.4
Their solution: 620 - 37.4p ≤ 450
They both evaluate to the same decimal: p ≥ 4.545454... or 50/11
But the unit test says I'm wrong. What gives?
Is it just preferred formatting?
(4 votes)
• I have been having this same problem myself.
Although your answer is also correct, they want you to use their inequality.

Renna pushes the elevator button, but the elevator does not move. The mass limit for the elevator is 450 kilograms, but Renna and her load of identical packages mass a total of 620 kg. Each package has a mass of 37.4 kg. 620-37.4p is less than or equal to 450 which means that with all the packages that she subtracts, the weight will be taken away from 620. I think you are all good with the rest, but p=5 because you can't take out 4.545454... packages from the load. 5 would be the answer.

Hope this helps.
(6 votes)
• I have a question from my textbook which I got it wrongly and I don't know why.
Here it is: The sum of 3 consecutive odd numbers is greater than 100. What is the minimum value of the smallest odd munber among them?
I wrote an equation: x+x+2+x+4 greater than 100
And my answer: 31 over 1 over 3 / 94/3
But the corrext answer is 33.
(4 votes)
• Adding x + (x+2) + (x+4) with x = lowest number
3x +6 > 100 thus, 3x > 94 which gives x > 31 +1/3
so x has to be the next odd number > 31 + 1/3 or 33
(1 vote)
• I will help you now that I´m in college!
(4 votes)
• I don't get how they give you the tools to answer one specific problem and they dump on you problems that has nothing to do with the equation that they helped you to understand, I just don't think that's fair, why do they give you the tool to do the wrong problem and then they're like " How come you don't know this thing we didn't tell you? you get a baaaaaaad score!" ?
(4 votes)
• I don't know what you mean by this. Please elaborate by giving a example.
(2 votes)
• Are there any keywords to help me know if the inequality is greater than, less than, greater than or equal to or less than or equal to. I already know that: at least = greater than or equal and at most = less than or equal. Any keywords will be really helpful.
(1 vote)
• Great chart! You are a great explainer!
(1 vote)

## Video transcript

A popular R&B band recently returned from a successful three-city tour where they played to at least 120,000 people. My brain immediately says that's greater than or equal to 120,000. If they had an audience of 45,000 in Mesa and another 33,000 in Denver, how many people attended their show in Las Vegas? So let's say Las Vegas, I'll just use l for Las Vegas. So the number of people who attended their show in Las Vegas plus the number that attended their show in Mesa, which is 45,000, plus the number of people that attended their show in Denver, which is 33,000-- those are three cities right there, Las Vegas, Mesa, and Denver-- that has to be at least 120,000 people. Or another way of interpreting that is greater than or equal to 120,000. So to figure out how many people attended their show in Las Vegas, we just solve for l on this inequalty. So if we simplify this left-hand side, we get the number of people in Las Vegas plus-- what's 45,000 plus 33,000, that is 78,000-- 78,000 is going to be greater than or equal to 120,000. Now to isolate the l on the left-hand side of the inequality, we can subtract 78,000 from both sides. So minus 78,000, minus 78,000 on the left-hand side, these cancel out. And we're just left with the number of people who attended the show in Las Vegas is going to be greater than or equal to 120,000 minus 78,000. So 120,000 minus 80,000 is 40,000, and it's going to be another 2,000. So the number of people who attended Las Vegas is going to be greater than or equal to 42,000 people. And we're done, that's it