You have the following equation for the cost of renting a car for x number of miles driven:
y = 0.15x + 65
If you travel 70 miles, then, x = 70 and you obtain for the cost y:
y = 0.15(70) + 65
y = 10.5 + 65
y = 75.5
Hence, the cost of renting a car to drive 70 miles is $75.5