the simple interest on a certain sum of money at the rate of 5 % p . a . for 8 years is rs . 840 . at what rate of interest the same amount of interest can be received on the same sum after 5 years ?
"solution s . i . = rs . 840 , r = 5 % , t = 8 years . principal = rs . ( 800 x 840 / 5 x 8 ) = rs . 2100 . now , p = rs . 2100 , s . i . = rs . 840 , t = 5 years . ∴ rate = ( 100 x 840 / 2100 x 5 ) = 8 % . answer b"
multiply(divide(divide(840, 5), divide(divide(840, 8), divide(5, const_100))), const_100)