A can contains a mixture of two liquids P & Q in the ratio 9 : 5. When 7 ltrs of mixture is drawn off & the can is filled with Q, the ratio of P & Q become 3 : 2. How many litres of liquid P was contained by the can initially ?

Let the initial quantity of liquids P and Q be 9x litres and 5x litres, respectively. So, total mixture = 14x litres When 7 litres of mixture is drawn off, Quantity of P removed = 7 × 9/14 = 4.5 litres Quantity of Q removed = 7 × 5/14 = 2.5 litres Remaining quantity of P = 9x – 4.5 Remaining quantity of Q = 5x – 2.5 Now, the can is filled with 7 litres of Q. So, final quantity of Q = 5x – 2.5 + 7 = 5x + 4.5 According to the question, {9x - 4.5}/{5x + 4.5} = {3/2} Or, 2(9x – 4.5) = 3(5x + 4.5) Or, 18x – 9 = 15x + 13.5 Or, 3x = 22.5 So, x = 7.5 Therefore, initial quantity of liquid P = 9x = 9 × 7.5 = 67.5 litres