Acar travels around a circular track. the inside wheels follow along the line of the inner circle, and the outer wheels follow along the line of the larger circle. the radius of the larger circle is 25 ft, and the radius of the smaller circle is 21 ft. determine how much farther the outer wheels would travel than the inner wheels after one revolution.

So, basically what they are asking for is the circumference (which is like the perimeter) of the inner and outer circles. 

Circumference is: C = 2πr

The radius of the two circles are given so all you need to do is plug it in.

Circumference of the bigger circle (outer tire) is 157ft. Circumference of the smaller circle (inner tire) is 132ft.

The exact answer is 157.07-131.88 = 25.19ft ≈ 25ft