Math question 8th grade class

Question

A plumber charges $40 set fee for each job plus an hourly rate. The table below shows t, the total charge, in dollars for a job that last h hours.

hours work total charge

h t

2 $120

4 $200

7 $320

9 $400

which equation models the relationship between h and t?

Answer 1

m = (200 - 120)/(4 - 2)

m = 80/2

m = 40

y = 40x + 40