In a solution water is 45%. When 18 liters more water is added the new concentration of water becomes 60%. Find the initial quantity of water in the solution.

Let the initial total solution be T liters. Water is 45% of T = 0.45T. After adding 18L water, new water = 0.45T + 18 and new total = T + 18. Given new water concentration is 60%: (0.45T + 18)/(T + 18) = 0.6. Solving: 0.45T + 18 = 0.6T + 10.8, so 7.2 = 0.15T, giving T = 48L. Initial water = 0.45 × 48 = 21.6L. Option A (36L) would mean initial total was 80L, which doesn't satisfy the 60% condition.