13. The function y = 40(x - 1) + 70 can be used to determine the cost in dollars
for renting a trampoline park for a birthday party for x hours. What is the rate of
change of the cost in dollars to rent the trampoline park with respect to time?
A
$30 per hour
$40 per hour
B
с
$60 per hour
D
$110 per hour