A runs 240 m in 30 seconds. He gives B a start of 40 m in a 240 m race, and they finish together. How long does B take to run 240 m?

Explanation

1. 01

   B runs 200 m in A's 30 seconds, so B's speed is $\frac{200}{30} = \frac{20}{3}$ m/s.

2. 02

   240 m takes B $240 \times \frac{3}{20} = 36$ seconds.