Question

The cruise control feature on a car is designed to maintain a set speed. If the car’s actual speed never varies by more than three mph, what is the difference between the maximum and minimum speed of the car when cruise control is used

Answer 1

If the speed varies by 3 mph while cruising, it means that the care can be 3 mph slower, or 3mph faster than it should be.

To find the different in these min and max speeds, you have to substract them.

If the car travels at

min: x-3 mph
max: x+3 mph

then the difference is

(x+3) - (x-3) = 6

or, if you want to keep it simple:

3 - (-3) = 6