The Drizzle Pvt. Ltd:, a squash company has 2 cans of juice. The first contains 25% water and the rest is fruit pulp. The second contains 50% water and rest is fruit pulp: How much juice should be mixed from each of the containers so as to get 12 litres of juice such that the ratio of water to fruit pulp is 3:5? 

Let's assume that quantities of juice taken from the first and second cans be x and y respectively.

So we can say that  x+y = 12                                                                             ...(1)

Net quantity of water in resulting mixture =$$\frac{25}{100}*x+\frac{50}{100}*y$$

Ratio of water to pulp in resulting mixture = 3:5 hence the mixture will contain $$\frac{3}{3+5}th=\frac{3}{8}th$$ part as water.

                                  $$\frac{25}{100}*x+\frac{50}{100}*y=\frac{3}{8}*(x+y)$$

                                  $$\frac{x}{4}+\frac{y}{2}=\frac{3}{8}*(12)$$    (Since x+y=12 )

                                     $$x+2y=18$$                                                                 ...(2)

                   Solving equation (1) and (2) for x and y 

                                                x=6 , y=6