A certain amount of 70% acetic acid was added to 1 liter of 10% acetic acid and 20% acid

A certain amount of 70% acetic acid was added to 1 liter of 10% acetic acid and 20% acid was obtained. How much acid was added?

To solve this problem, we introduce a conditional variable “X”, through which we denote the number of liters of 70% acetic acid, which was added to 1 liter of 10% acetic acid to obtain 20% acetic acid.

Then, based on the data of the problem, we will compose the following equation: (0.1 x 1 + 0.7 x X) / (1 + X) = 0.2.

Solving this equation, we get 0.1 + 0.7X = 0.2 + 0.2X or 0.1 = 0.5X or X = 1/5 liter or 0.2 liter.

Answer: to 10% acetic acid, add 0.2 liters of 70% acetic acid to get 20% acetic acid.