A is 2 1/3 times as fast as B. If A gives B a start of 80 m, how long should the race course be so that both of them reach at the same time?
Answer: C
Speed of A : Speed of B = 7/3 : 1 = 7 : 3
It means, in a race of 7 m, A gains (7-3)=4 meter
If A needs to gain 80 metre, race should be of 7/4×80 = 140 metre