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# Percent word problem: 78 is 15% of what number?

In this example, you working with us to find the number that is expressed as a given percentage. We'll create a simple algebraic equation to solve! Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• Couldn't you have just divided 78 by 15 then multiple it by 100 to get the same thing
• Sal likes to explain things the long way so that you have a thorough understanding of what you're doing. There are actually shortcuts for a lot of the steps in these videos, but it's better to what you're doing and why you're doing it. I'm guessing that in the more advanced videos he explains the shortcuts.
• What is markup?
• why does the video have nothing to do with the questionsevertime
• What about problems that show everything but the %? What about a question that asks to find percentage?

For example: an Item is \$6.95 before tax, and after Tax it is \$7.61. How can I find the tax which is a percent?
• Try subtracting \$6.95 from \$7.61. If it dose not work, tell me please.
• 78 is 15% of what number?

Literally divide 78 by 0.15 and it gives you the answer.
The way shown in the video was pretty long.
• so in another way can we write another equation like this for this?^^
78/n = 15/100 ?
• Yes she is doing .15x=78 in a inequality form.
Hope this helps!
• there is two of the same videos
• why dose he put a two on the fifteen while he's dividing?
• At that point, Sal is mulitplying 15(5). The 2 is part of his calculations. Looks like he didn't want to write the full calculation off to the side. 5(5) = 25. He writes the 5 down on the right and carries the "2" above the 15 to keep track of it.
• `can we do it this way?78/n = 15/100 ?`