Question

A 70 litres mixture of milk and water contains 20% of water. what quantity of additional water be mixed so that the water content in the mixture becomes 30%?

Answer 1

14 + x = (30*(70 +x))/100

14+x = (3*70+3x)/10

10(14+x) = 210+ 3x

140+10x = 210 + 3x

Transposition on both sides

10x - 7x = 210 - 140

7x = 70

x = 10