Answer:
It will take 17.5 minutes to reach 50 degrees F.
Explanation:
Current temperature = -13 degrees F
With the engine on, the temperature goes up by 3.6°F per minute.
Let us assume that it takes x minutes to reach 50 degrees F.
So, the time taken will be =

=>

=>

x = 17.5 minutes
The expression that tells how much the temperature needs to change from -13°F to 50°F is :

It will take 17.5 minutes to reach 50 degrees F.