A can contains a mixture of liquids A and B is the ratio 7:5. When 3 litres of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7:9. How many liter of liquid A was contained by the can initially? Choose the correct choice from the following answers
A) 7  B) 10  C) 12  D) 14  E) 16
Ci*Vi = Cf*Vf   (7/12)*(V1 - 3) = (7/16)*V1   (V1 - 3)/V1 = 3/4   3 accounts for the difference of 1 on ratio scale so Initial volume = V1 = 4*3= 
<gadget id="calculator">4*3</gadget>
<output>12</output>
12 litres.   7/12 of the initial mixture was liquid A so liquid A was   (7/12)*12= 
<gadget id="calculator">  (7/12)*12</gadget>
<output>7</output>
7 litres.   7nswer : 7
<result>A</result>
A can contains a mixture of liquids A and B is the ratio 7:5. When 3 litres of mixture are drawn off and the can is filled with B, the ratio of A and B becomes 7:9. How many liter of liquid A was contained by the can initially?