on selling 15 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 15 balls ) - ( s . p . of 15 balls ) = ( c . p . of 5 balls ) c . p . of 10 balls = s . p . of 15 balls = rs . 720 . c . p . of 1 ball = rs . 720 / 10 = rs . 72 . answer : option e"
divide(720, subtract(15, 5))