Let x l of mixture be taken from 1st vessel and y l of the mixture be taken from 2nd vessel and kept in 3rd vessel so that (x+y) l of the mixture may contain a mixture of 25 l of milk and 10 l of water.
A mixture of x l form 1st vessel contains 2430x=45x l of milk and x5 l of water and a mixture of y l from 2nd vessel contains 3y5 l of milk and 2y5 l of water.
∴ 45x+35y=25.........(i)
x5+25y=10........(ii)
Solving equation (i) and (ii) x=20 litres and y=15 litres.