A chemist has two solutions.One contains 30%acid and 70%water and the other contains 70%acid and 30%water.How many litres of each solution should he mix to make 100 litres of solution containing 40%acid and 60% water?

Question

A chemist has  two solutions.One contains 30%acid and 70%water and the other contains 70%acid and 30%water.How many litres of each solution should he mix to make 100 litres of solution containing 40%acid and 60% water?

phi · Answer

say you have x of the 30%  and y of the 70%
then you can say
x+y= 100

also, set up an equation equating the amount of acid:
0.3x + 0.7y = 0.4*100

phi · Answer

now solve the 2 equations