How much L of 26% of alcohol solution should be mixed

Question

One antifreeze solution is 26% alcohol and another is 20% alcohol. How much of each mixture should be added to make 45 L of a solution that is 24% alcohol?

Answer 1

You need twice as much 26% as 20%. 24 is within 2 of 26, within 4 of 20. 4 is twice 2

30 is twice 15. 30+15 = 45. You need 30 L of 26% and 15L of 20%

26x + 20(45-x) = 45(24)

26x -20x = 45(24) -(20(45)

6x = 4(45) = 180

x = 180/6 = 30 L of 26%

45-x = 45-30 = 15L of 20%