Hi, Kara. Let x = the amount of 40% concentration and y = the amount of 25% concentration. We now that the mixture can be represented as:
x + y = 84 since the mixture is a total of 84 L. Let's solve for y.
y = 84 - x
To find the specific amount of each concentration needed, we can use the following formula:
.40x + .25y = .35(84) which becomes:
.40x + .25(84 - x) = 29.4
Multiply both sides of the equation by 100 to eliminate the decimals.
40x + 25(84 - x) = 2940
40x + 2100 - 25x = 2940
15x + 2100 = 2940
15x = 840
x = 56
If x = 56, then y = 84 - 56 = 28
Hence, we need 56 L of 40% concentration and 28 L of 25% concentration.
