Neil arrives home first and says the air conditioner at 75°. When Sandy arrives, she lowers it by 10°. What is the magnitude of this change in thermostat levels?

Answer 1

The initial thermostat level is 75°. When Sandy lowers it by 10°, the new thermostat level becomes:

75° - 10° = 65°.

The magnitude of the change in thermostat levels is simply the amount it was lowered, which is 10°.