On selling 17 balls at Rs. 720, there is a loss equal to the cost price of 5 balls. The cost price of a ball is	Options
A) 20	B) 30	C) 40	D) 50	E) 60

Rationale: "( c . p . of 17 balls ) - ( s . p . of 17 balls ) = ( c . p . of 5 balls ) c . p . of 12 balls = s . p . of 17 balls = rs . 720 . c . p . of 1 ball = rs . 720 / 12 = rs . 60 . answer : e"
Answer: E