A sum of money at simple interest amounts to Rs. 1560 in 4 years and to Rs. 1590 in 6 years. The sum is:	Pick.
A) rs . 1400  B) rs . 1450  C) rs . 1500  D) rs . 1550  E) rs . 1525

Rationale: "s . i . for 2 years = rs . ( 1590 - 1560 ) = rs . 30 . s . i . for 4 years = rs . ( 30 x 2 ) = rs . 60 . principal = rs . ( 1560 - 60 ) = rs . 1500 . answer : option c"
Answer: C