On selling 17 balls at Tk. 840 there is a loss equal to the cost price of 5 balls. The cost price of a ball is-

Question: On selling 17 balls at Tk. 840 there is a loss equal to the cost price of 5 balls. The cost price of a ball is-

Solution:
Let,
The cost price of 1 ball is = Tk. x
The cost price of 17 balls is = Tk. 17x

We know,
Cost price - Selling price = Loss
17x - 840 = 5x
⇒ 12x = 840
⇒ x = 840/12
∴ x = 70

∴ The cost price of 1 ball is Tk. 70