In a 300 m race A beats B by 30 m. Running at the same speeds, by how many metres does A beat B in a 1 km race?

Explanation

1. 01

   B runs $\frac{270}{300} = \frac{9}{10}$ of A's distance in the same time.

2. 02

   When A runs 1,000 m, B runs 900 m: A wins by 100 m.