A solution of salt and water contains 40% salt, 175 ml water is evaporated and now percentage of salt in solution becomes 60%. Find the initial quantity of solution ?

Let initial solution = x ml. Initial salt = 0.4x, water = 0.6x. After evaporating 175 ml water: new water = 0.6x - 175, salt = 0.4x. Total new volume = x - 175. Salt percentage = 0.4x / (x - 175) = 0.60. Solving: 0.4x = 0.6x - 105, so 0.2x = 105, x = 525. Initial solution was 525 ml. Verification: Initial: 40% of 525 = 210 ml salt, 315 ml water. After evaporation: 210 ml salt, 140 ml water (315-175). Total = 350 ml. Salt % = 210/350 = 60%. Option C (525 ml) is correct.