Question

A chemistry teacher needs to mix a 20% salt solution with a 80% salt solution to make 25 qt of a 44% salt solution. How many quarts of each solution should the teacher mix to get the desired result?

Answer 1

set up a system of equations

let x = number of qts from the 20% salt solution
let y = number of qts from the 80% salt solution

one equation will describe the number of total qrts and the other will describe the total amount of salt

Answer 2

x and y must add up to 25, therefore

x + y = 25

the total amount of salt is 44% times 25, or (0.44*25). each individual solution's contribution to the mixture can be described as (percent salt content)*amount of solution

therefore

0.80x + 0.20y = 0.44*25

Answer 3

so in the end you must solve

x + y = 25
0.80x + 0.20y = 0.44*25

by elimination, substitution, or graphing