Remove and replacing of mixture in jar?

Question

A jar contained a mixture of two liquids A and B in the ratio 4 : 1. When 10 liters of the mixture was taken out and 10 liters of liquid B was poured into the jar, this ratio became 2 : 3. the quantity of liquid A contained in the jar initially was ?

16 liters of 40 liters ?

Answer 1

Let $|B|=x$.

Thus, we obtain the following equation: $$\frac{4x-8}{x-2+10}=\frac{2}{3},$$ which gives $x=4$ and the answer is $16$.