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 = ?

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
$$\left[ {\frac{{\left( {100 + x} \right)}}{{100}} \times \frac{{125}}{{100}} \times \frac{{120}}{{100}} \times P} \right] = $$       $$\left[ {\frac{{165}}{{100}} \times P} \right]$$
$$\eqalign{ & \Rightarrow \left( {100 + x} \right) = \frac{{165 \times 100 \times 100}}{{125 \times 120}} \cr & \Rightarrow x = 10\% \cr} $$