After mixing 60% and 20% acid solutions, 800 g of a 40% solution was obtained.

After mixing 60% and 20% acid solutions, 800 g of a 40% solution was obtained. How many grams of each solution are mixed.

To solve the problem, we compose a system of equations in which the amount of the first solution will be 0.6 * x, the amount of the second solution is 0.2 * x, and the amount of the third solution will be equal to 0.4 * 800 = 320 grams.
In this case, we get 2 equations.
Where x + y = 800 grams.
0.6 * x + 0.2 * y = 320 grams.
We express the value of the number x from the first equation.
We will receive.
x = 800-y.
Substitute this value into the second equation.
0.6 * (800-y) + 0.2y = 320.
480-0.6 * y + 0.2 * y = 320.
-0.6 * y + 0.2 * y = 320-480.
-0.4 * y = -160.
0.4 * y = 160.
y = 160 / 0.4.
y = 400 grams. There was a second solution.
x = 800-400.
x = 400 grams. There was the first solution.