Final answer:
To find the temperature at 7:00, subtract the temperature drop from the initial temperature. Starting from -2° at 3:00, after a 19° drop, the temperature at 7:00 is -21°.
Step-by-step explanation:
At 3:00, the temperature was -2°. Four hours later, the temperature dropped 19°. To find out the temperature at 7:00, we need to subtract the drop in temperature from the initial temperature.
Initial temperature at 3:00 = -2°
Drop in temperature over four hours = 19°
Temperature at 7:00 = Initial temperature - Drop in temperature
Temperature at 7:00 = (-2°) - (19°) = -21°
Therefore, the temperature at 7:00 is -21°.