The front wheels of a wagon are 7 feet in circumference and the back wheels are 9 feet in circumference. When the front wheels have made 10 more revolutions than the back wheels, what distance, in feet, has the wagon gone?
A. 126
B. 180
C. 270
D. 315
E. 630
The distance traveled is the circumference of the wheel times the number of revolutions. If r is the number of revolutions of the back wheel, r + 10 will be the number of revolutions of the front wheel. They will have traveled the same distance, so 7 ft. X (r + 10) = 9 ft. X r, and r = 35. The wagon has gone 9 ft. X 35 revolutions = 315 feet.