the simple interest and the true discount on a certain sum for a given time and at a given rate are rs . 88 and rs . 80 respectively . the sum is :
"sol . sum = s . i . * t . d . / ( s . i ) - ( t . d . ) = 88 * 80 / ( 88 - 80 ) = rs . 880 . answer a"
divide(multiply(88, 80), subtract(88, 80))