A trader bought a car at 20% discount on its original price. He sold it at a 70% increase on the price he bought it. What percent of profit did he make on the original price?
Choose the correct option:
A) 17 %
B) 72 %
C) 12 %
D) 82 %
E) 36 %

Rationale: "original price = 100 cp = 80 s = 80 * ( 170 / 100 ) = 136 100 - 136 = 36 % answer : e"
Answer: E