Question

unplug it! plumbing charges an hourly fee of $85, plus a one-time base fee of $115 to diagnose any issue.
which equation gives the average cost $y$ in dollars for $x$ hours of plumbing?
a $y=\frac{115x + 85}{x}$
b $y=\frac{85x + 115}{x}$
c $y = 85$
d $y = 85x + 115$

Explanation:

Step1: Calculate total cost

Total cost = Hourly cost + Base fee = $85x + 115$

Step2: Find average cost

Average cost = $\frac{\text{Total cost}}{\text{Number of hours}}$
$y = \frac{85x + 115}{x}$

Answer:

B. $y=\frac{85x+115}{x}$