Q:

A) 10 | B) 20 |

C) 21 | D) 25 |

Answer: C) 21

Explanation:

Explanation:

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

Quantity of A in mixture left =$\left(7x-\frac{7}{12}\times 9\right)=\left(7x-\frac{21}{4}\right)$ litres.

Quantity of B in mixture left = $\left(5x-\frac{5}{12}\times 9\right)=\left(5x-\frac{15}{4}\right)$litres.

$\frac{\left(7x-{\displaystyle \frac{21}{4}}\right)}{\left(5x-{\displaystyle \frac{15}{4}}\right)+9}=\frac{7}{9}$

$\Rightarrow \frac{28x-21}{20x+21}=\frac{7}{9}$

$\Rightarrow x=3$

So, the can contained 21 litres of A.