Answer:
The temperature dropped 29 °F
Explanation:
Temperature at sunrise = -3 °F
+ Temperature rise = + 18
Temperature at noon = 15 °F
Temperature at sundown = -14 °F
- Temperature at noon = - 15
Temperature change = -29 °F
The negative sign shows that the temperature dropped.
The temperature dropped by 29 °F.
The changes may be easier to see on a number line. If you start at -3 °F and increase the temperature by 18 °F, you end up at 15 °F. If the temperature then changes to -14 °F, it has dropped by 29 °F.