Question

problem 2: an electrician charges $10 for a house call. he also charges $20 per hour as his labor. on a house call, if his bill was $150, then how many hours did he work?

Explanation:

Step1: Subtract the house - call charge

The total bill is $150$ and the house - call charge is $10$. So the amount charged for labor is $150 - 10=140$.

Step2: Calculate the number of hours

The labor charge is $20$ per hour. Let the number of hours be $h$. We know that the labor cost formula is $C = 20h$. Since $C = 140$, then $h=\frac{140}{20}$.

Answer:

$7$ hours