If A is 20% more than B and B is 30% less than C, then by what percent C is greater than A ?

Given A is 20% more than B and B is 30% less than C

It implies that $A=\frac{120}{100}B$ and $B=\frac{70}{100}C$

Hence, 

$\begin{array}{rcl}C& =& \frac{100}{70}B\\ & =& \frac{10}{7}\times \frac{10}{12}A\\ & =& \frac{100}{84}A\\ & =& 1.19A\end{array}$

Therefore, $C$ is $19\%$ more than $A$