Five litres of water is added to a certain quantity of pure milk, costing ₹60 per litre. If by selling the mixture at the same price as before, a profit of 20% is made, then the amount of pure milk in the mixture is :

25 litres

The correct answer is Option (2) → 25 litres

Cost of Pure Milk = Rs. 60 per litre

Let the quantity of pure milk be $x$ litre

Selling price per litre = Rs. 60

Profit percentage = $20\%$

Cost price = $60x$

Total volume = $(x+5)L$

and,

Selling price, $SP=60(x+5)$

$⇒60(x+5)=60x×\left(1+\frac{20}{100}\right)$

$⇒72x-60x=300$

$⇒12x=300$

$⇒x=\frac{300}{12}=25$ litres