the temperature is 10 degrees F at 7 pm, and -2 degrees F at 7 am the next morning. How much did the temperature change between 7 pm and 7 am

Question

From 7th grade Go Math workbook 2.2. 

Answer 1

T₁ = initial temperature = 10°F

 

T₂ = final temperature = -2°F

 

ΔT = temperature change = T₂ - T₁

 

ΔT = -2°F - 10°F = -12°F

 

The minus sign indicates a temperature drop, so the temperature dropped by 12°F from 7:00 pm to 7:00 am

 

 

Answer 2

To find a change in something, you use subtraction. It's like if you had 10 donuts and brought you enough that you had 16, how many did I give you? (16-10=6).

 

So for this problem, you are solving the equation: 7F -  -2F =?

 

When you subtract a negative number, it works like addition. So your answer is 7 + 2 = 9