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Lesson 6: Adding & subtracting negative numbers: variables

# Ordering expressions

Let's get some practice thinking about adding and subtracting variables representing positive and negative numbers on the number line.

## Want to join the conversation?

• At , if a is -0.7 and b is -0.2, lets say, then, -0.7-(-0.2) = -0.5 (a-b) which is definitely, bigger than a and -0.7-0.5, would be -1.2, which is smaller than a. So, can someone please explain
• Yes, a-0.5 is smaller than a, and a is smaller than a-b. So it is ordered from least to greatest as a-0.5, a, and a-b. That's what Sal wrote. He didn't switch around the three blocks for technical reasons, which he explains at .
• when will we have to use this i the real world?
• thats how i feel were doing all this stupid stuff that we most likely wont need irl
• He talks so slow I watch this at 1.5x speed
lol
• Is dream a life or is life a dream
• Life is dream
• Has anyone seen third stage aqualine before? The other stages of Aqualine look perfect, but the third stage is terrible:
• Does anyone actually understand this stuff? :o Even after watching the video I still don't understand :/
• The way that I do it is I give the letters numbers. Say if the problem has z, I would assign z to be 2. Then I would solve the problems as if I was doing individual problems. Then I would order the expressions.
• At i tested that logic and its not true. Or am I getting it wrong? Like if i substitute q with -10 and n with -2 my expression will be -10-(-2) = -8. So I'm not getting +ve as Sai explained that it doesn't matter. Or how am i to approach his logic?
• Now look, you substituted -10 for q and -2 for n. But the thing is that q on the number line is a positive number for you can't substitute with a negative.
• i shall not watch thy video for i am no peasant amoung this divine website. I shal use thy brain and not these videos
• You get 850 energy points if you watch the whole video without skipping anything, you know!
(1 vote)
• Which is greater negative 3 or negative 2.