sorry if this took too long but tried my best to hurry
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When the table says that there has been a RISE, that means that you should ADD. When the table says there has been a FALL, that means you should SUBTRACT.
The second row and the second column is saying a RISE, meaning that you should ADD 8 and 2. 8 + 2 = 10. So the answer for that one would be 10 degrees celcius (third column, second row.) The numbers in bold are your equation for the second row and fourth column.
Here are the rest: AT MEANS AFTERNOON TEMPERATURE :)
3rd row: AT = -8 [degrees celcius] EQUATION: -2 - 6 = -8
4th row: AT = 3 [degrees celcius] EQUATION: -4 + 7 = 3
5th row: AT = -3 [degrees celcius] EQUATION: 6 - 9 = -3
6th row: AT = -10 [degrees celcius] EQUATION: -5 - 5 = -10
7th row: AT = 0 [degrees celcius] EQUATION: 7 - 7 = 0
Woohoo! We're done with that part now.
(b) So, as I said before, a RISE means you must ADD. If you have a rise in -7 degrees celcius, how would you write that mathematically? You would write it like this: + ( - 7 ). You are ADDING NEGATIVE SEVEN. I know it sounds weird, but it is what it is. NOW. Adding negative 7 IS THE EQUIVALENT of saying subtract seven. Here's an example:
10 + ( - 7 ) = 3 (this is true)
10 - 7 = 3 (this is also true)
Therefore, for b you would say that you agree because +(-7) is the equivalent of say 'minus 7'.
Hopefully, you can use what I explained to help you with number 2. If you need more help you can just comment on this post and I'll help you. :))