just reposting from the intermediate forum to have more feedback
plz show your works and which equations did used thanks
A can contains a mixture of two liquids A & B in proportion 7:5 When 9 litres of mixture is drawn off and the can is filled with liquid B, the proportion of A & B becomes 7:9. How many litres of liquid A was contained by the can initially?
9 lit of mix is drawn; so amount of A drawn = 21/4 lit B=15/4 lit
final amount : (A-21/4) (B-15/4+9)
ratio is (A-21/4)/(B+21/4)=7/9
solve for A
ans is 21