A sum of money lent out at S.I. amounts to Rs. 820 after 2 years and to Rs. 1020 after a further period of 5 years. The sum is?	Pick one:  A) rs . 440  B) rs . 500  C) rs . 540  D) rs . 740  E) rs . 840

Rationale: "s . i for 5 years = ( 1020 - 820 ) = rs . 200 . s . i . for 2 years = 200 / 5 * 2 = rs . 80 . principal = ( 820 - 80 ) = rs . 740 . answer : d"
Answer: D