math
posted by morgan on .
Ashley can ride her bike to work in 2/3 of an hour. When she drives to work it takes 1/3 of an hour. If she drives 12 miles per hour faster than she rides her bike, how fast does she ride her bike?

Let x = bike speed and x+12 = car speed. Since they both go the same distance:
2/3x = 1/3(x+12)
Solve for x.