(percentage problem) requires detailed explanation process (does not accept ternary linear equation solution) A has two containers with different concentrations of alcohol solution are 10 liters and 20 liters respectively. Now take out the same volume of solution from two containers and pour it into each other's containers. After mixing, the concentration of alcohol solution in two containers is equal. What is the volume of solution taken out?

(percentage problem) requires detailed explanation process (does not accept ternary linear equation solution) A has two containers with different concentrations of alcohol solution are 10 liters and 20 liters respectively. Now take out the same volume of solution from two containers and pour it into each other's containers. After mixing, the concentration of alcohol solution in two containers is equal. What is the volume of solution taken out?

Because the concentration of the two new alcohol solutions is the same, the new alcohol solution is the concentration of the alcohol solution in container a and B together. That is to say, most of the new alcohol is obtained by mixing the two containers of alcohol according to the ratio of 10:20. Therefore, the weight of the two containers of new alcohol is still 10 L and 20 L. therefore, the weight of the new alcohol in container B is: 10:20 = 1:2, 20 × 1 / (1 + 2) = 20 / 3 L