In a 100 m race, A beats B by 20 m. What is the ratio of A's speed to B's?

Explanation

1. 01

   While A runs 100 m, B runs $100 - 20 = 80$ m in the same time.

2. 02

   In equal times, speeds are in the ratio of distances: $100 : 80 = 5 : 4$.