a sum of money at simple interest amounts to rs . 815 in 4 years and to rs . 854 in 5 years . the sum is :
"sol . s . i . for 1 year = rs . ( 854 - 815 ) = rs . 39 . s . i . for 4 years = rs . ( 39 * 4 ) = rs . 156 . â ˆ ´ principal = rs . ( 815 - 156 ) = rs . 659 answer a"
subtract(815, divide(multiply(subtract(854, 815), 4), 5))