on selling 17 balls at rupees 720 there is a loss equal to the cost price of 5 balls. find the cost price of a ball

Let the cost price of a ball be Rs. x.

So, the CP of 17 balls is Rs. 17x.

The CP of 5 balls is Rs. 5x.

Since Loss = CP - SP

So, 5x = 17x - 720

On solving, we get

12 x = 720

that is, x = 60

So, the cost price of a ball is Rs. 60.