A person borrows Rs. 7000 for 2 years at 4% p.a. simple interest. He immediately lends it to another person at 6 p.a for 2 years. Find his gain in the transaction per year. Pick one:  A) 100 rs  B) 150 rs  C) 140 rs  D) 180 rs  E) 200 rs

Rationale: "gain in 2 years = [ ( 7000 * 6 * 2 ) / 100 ] - [ ( 7000 * 4 * 2 ) / 100 ] 840 - 560 = 280 gain in 1 year = ( 280 / 2 ) = 140 rs answer : c"
Answer: C