A can contains a mixture of two liquids A and B is the ratio 7 : 5. When 9 litres of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7 : 9. How many litres of liquid A was contained by the can initially?

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Accepted Answer

Suppose the can initially contains 7x and 5x of mixtures A and B respectively.

Quantity of A in mixture left =	❨	7x -	7	x 9	❩	litres =	❨	7x -	21	❩ litres.
			12						4

Quantity of B in mixture left =	❨	5x -	5	x 9	❩	litres =	❨	5x -	15	❩ litres.
			12						4

∴

❨	7x -	21	❩
		4

=

7

❨	5x -	15	❩ + 9
		4

9

⟹	28x - 21	=	7
	20x + 21		9

⟹ 252x - 189 = 140x + 147

⟹ 112x = 336

⟹ x = 3.

So, the can contained 21 litres of A.

A can contains a mixture of two liquids A and B is the ratio 7 : 5. When 9 litres of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7 : 9. How many litres of liquid A was contained by the can initially?

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