times both sides by 7 (to get rid of the 7 on the left)
Add 5 to both sides
The average temperature change per hour is -3 degrees C
b) Use mental math to calculate 49% of 162.
a. To find this answer you will need to turn that percentage into a decimal. 49%=.49
Then, you will need to multiply 49x162
Estimated is 79.00
b. 49% of 162 would be 79.38