The price of a jewellery, passing through three hands. Rises on the whole by 65%. If the first and the second sellers earned 20% and 25% profit respectively, the profit earned by the third seller is = ?

Answer: Option C

Lets assume the original price of the jewel = Rs. P
and profit earned by the third seller= x%
Then, ( 100 + x )% of 125% of 120% of P = 165% of p
$$\left[\frac{\left(100+x\right)}{100}\times \frac{125}{100}\times \frac{120}{100}\times P\right]=$$       $$\left[\frac{165}{100}\times P\right]$$
$$\begin{array}{rl}& \Rightarrow \left(100+x\right)=\frac{165\times 100\times 100}{125\times 120}\\ & \Rightarrow x=10\%\end{array}$$