Answer:
Joe's Plumbing charges more per hour ($45) than Mark's Plumbing (S40)
Step-by-step explanation:
Let
t ------> the number of hours
J(t) ---->the total amount in dollars that Joe's Plumbing charges
M(t) ---->the total amount in dollars that Mark's Plumbing charges
we know that
The linear equation in slope form is equal to

where
m is the slope or rate of the linear equation
b is the y-intercept (initial value)
In this problem we have
<em>Joe's Plumbing</em>

The slope or rate is equal to


Mark<em>'s Plumbing</em>

The slope or rate is equal to


therefore
Joe's Plumbing charges more per hour ($45) than Mark's Plumbing (S40)