The temperature at 5:00 a. m. was - 6 °F. By 3:00 p. m., the temperature had risen to a high of 36 °F. If the temperature at 8:00 p. m. decreased from the high by of the change in temperature in Fahrenheit degrees from 5:00 a. m. to 3:00 p. m., what was the temperature at 8:00 p. m.?

Let T denote temperature, °F

At 5:00 a. m.:

T = - 6 °F

At 3:00 p. m.:

T = 36 °F

The rise in temperature from 5:00 am is

36 - (-6) = 42 °F

At 8:00 p. m.:

The temperature decreased from the high of 36 °F by 42 °F (equal to the amount of increase from 5:00 a. m. to 3:00 p. m.).

Therefore the temperature at 8:00 p. m. is

36 - 42 = - 6 °F

Answer: - 6 °F