Question

Two vessel contain milk and water in the ratio 7:5 and 7:9

Answer 1

Amount of milk = 45 × 13/15 = 39 L

Amount of water = 45 - 39 = 6.

Let water to be added is x.

Then,

\frac{39}{6 + x}  =  \frac{3}{1}  \\ 18 + 3x = 39 \\ x = 7

Water to be added is 7 L