Question 796753
two equations for this

x + y = 40
number of liters of each type that add up to 40 quarts
6x + 2y = 3
how much of each percentage type to make the 3 percent

start off by multiplying 3 by 40 and putting that answer in the bottom equation

x  + y  = 40
6x + 2y = 120

now, we are going to solve this using the addition method, we want to get rid of the y then solve for x, so lets multiply the top line by -2

-2x -2y = -80
6x  + 2y = 120

add the two lines together

4x = 40

divide both sides by 4

x = 10

we now know the value of x, plug that number into our original equation and solve for y

x + y = 40
6(10) + 2y = 120
.....................
x + y = 40
60  + 2y  = 120
..................
x  + y  = 40
2y  = 60
.................
x  + y  = 40
y  = 30
.............

x = 1 and y = 30

we now know that it will take 10 quarts of 6 percent and 30 quarts of 2 percent to make the 3 percent solution