A sum of money lent out at S.I. amounts to Rs. 850 after 2 years and to Rs. 1020 after a further period of 5 years. The sum is?	Select the correct option.
A) s . 440	B) s . 500	C) s . 540	D) s . 782	E) s . 840

Rationale: "s . i for 5 years = ( 1020 - 850 ) = rs . 170 . s . i . for 2 years = 170 / 5 * 2 = rs . 68 . principal = ( 850 - 68 ) = rs . 782 . answer : d"
Answer: D