Q. ) If certain litres of Milk was mixed with 10 litres of water, the mixtures costs Rs 42/litre. If milk's cost was Rs 56/litre, how much litres of milk were mixed?
Assume that water has zero cost. The amount of milk is M.
0(10) + 56(M) = 42(10 + M)
56M = 420 + 42M
14M = 420
M = 30
