y=80x+16 with x representing the amount of hours rented.
Slope-intercept form is:
y=mx+b
In this case, y represents the total cost. m represents the amount per hour, x represents the amount of time, and b represents the number you add.
You would plug in the information you have (m=80 as it is $80 per hour; b=16 as it is added to the final sum):
y=80x+16
