Acar is moving at a rate of 65 miles per hour and the diameter of its wheels is 2 feet.
a) find the number of revolutions per minute the wheels are rotating.
b) find the angular speed of the wheels in radians per minute.

A) 910.37 rpm
b) 5720 radians per minute.

First, figure out how many feet per hour the car is moving.
65 * 5280 = 343200

Now figure out how many feet per minute the car is moving
343299 / 60 = 5720

Figure out the circumference of the tires in feet.
2 * pi = 2 * 3.1415926535...  = 6.283185

Divide the distance traveled by the circumference of the wheels
5720 / 6.283185 = 910.3663 rpm. Rounded to 2 decimal places is 910.37

There is 2 pi radians in a circle. So to convert from RPM, just multiply by 2*pi. So
910.37 * 2 * pi = 5720