The ratio of spirit and water in solution A is 3 : 4, and the ratio of spirit and water in solution B is 5 : 9. Later, 5 L of A is mixed wi…

Explanation

Solution A (5 L, 3 : 4): spirit 15/7 L, water 20/7 L. Solution B (6 L, 5 : 9): spirit 15/7 L, water 27/7 L. Mixture is 11 L with spirit 30/7 L and water 47/7 L. In 462 mL: spirit = 462 × 30/77 = 180 mL and water = 282 mL. For 1 : 2 the water must be 360 mL, so 360 − 282 = 78 mL must be added.