on selling 20 balls at rs . 720 , there is a loss equal to the cost price of 5 balls . the cost price of a ball is :
"( c . p . of 20 balls ) - ( s . p . of 20 balls ) = ( c . p . of 5 balls ) c . p . of 15 balls = s . p . of 20 balls = rs . 720 . c . p . of 1 ball = rs . 720 / 15 = rs . 48 . answer : option a"
divide(720, subtract(20, 5))