# Math Help - Equation of a Line

1. ## Equation of a Line

A Plumber charged $110 for a three-hour job and$160 for a five-hour job. At this rate, how much would he charge for an 8-hour job?

2. Let a be the initial cost, and b be the cost per hour. Then:

a + 3b = 110
a + 5b = 160

Solve the system for a and b; your answer will be a + 8b.