In a 200 m race A beats B by 20 m, and in a 200 m race B beats C by 20 m. By how many metres does A beat C in a 200 m race?

Explanation

1. 01

   When A runs 200 m, B runs $180$ m.

2. 02

   C runs $\frac{180}{200}$ of what B runs: $180 \times \frac{180}{200} = 162$ m, so A wins by $38$ m.