There is a 450 liters solution of sugar and water in a vessel which contains 20% sugar how much sugar should be mixed in the mixture so that the sugar becomes 25%?

30

In the mixture:

Sugar is 20% then water is 80%

In the new mixture,

Sugar is 25% then water is 75%

*In the process, sugar is added but water remains same.*

Therefore,

Water in Old Qty = Water in New Qty.

80% of 450 = 75% of New Qty.

New Qty. = 480 Litters

Hence,

Sugar added = 480 - 450 = 30