The milk and water in a mixture are in the ratio 7 : 5.

The milk and water in a mixture are in the ratio 7 : 5. When 15 litres of water are added to it, the ratio of milk and water in the new mixture becomes 7 : 8. The total quantity of water in the new mixture is

Let the quantity of milk in the
mixture = 7x litres and that of
water = 5x litres.
According to the question,

7x	=	7
5x + 15	=	8

⇒ 56x = 35x + 105
⇒ 56 x – 35 x = 105
⇒ 21x = 105

⇒ x =	105	= 5
	21

∴ Required quantity of water
= (5x + 15) litres
= 5 × 5 + 15 = 40 litres