In a race of 200 m, A can beat B by 31 m and C by 18 m. In a race of 350 m, C will beat B by ?

A:B = 200 : 169
A:C = 200 : 182
  $\frac{C}{B} = \frac{C}{A}\times \frac{A}{B}$ 

$\frac{182}{200}\times \frac{200}{169}$

=> 182:169

When C covers 182 m , B Covers 169 m
When C covers 350 m , B Covers  $\frac{169}{182}\times 350$
=> 325 m

So C beats B by (350 - 325) = 25 m.