On selling 12 balls at Tk. 720 there is a loss equal to the cost price of 4 balls. The cost price of a ball is-

Question: On selling 12 balls at Tk. 720 there is a loss equal to the cost price of 4 balls. The cost price of a ball is-

Solution:
Let,
The cost price of 1 ball is = Tk. x
The cost price of 12 balls is = Tk. 12x

We know,
Cost price - Selling price = Loss
⇒ 12x - 720 = 4x
⇒ 8x = 720
⇒ x = 720/8
∴ x = 90

∴ The cost price of 1 ball is Tk. 90