Answer:
0.5 liters of each will make 1 liter of 0.17% salt solution.
Explanation:
Let x = the amount of 0.07% solution
Let y = the amount of 0.27% solution
Both the amounts combined will make one liter.
x + y = 1
0.0007 of the x solution plus 0.0027 of the y solution will make 0.0017 of the 1 liter.
0.0007x + 0.0027y = 1*0.0017
Multiply the whole thing by 10000 to clear that horrid decimal.
7x + 27y = 17
NOW, you have a system of equations.
x + y = 1
7x + 27y = 17
You go about solving it normally. Multiply the first equation by -7, add them together, and solve for y.
-7x - 7y = -7
7x + 27y = 17
-----------------
20y = 10
y = 0.5
Substitute 0.5 for y in the first equation.
x + 0.5 = 1
x = 0.5
Well, if those answers are correct, you can substitute 0.5 for both x and y in the second equation, and it will work.
7(0.5) + 27(0.5) = 17
3.5 + 13.5 = 17
17 = 17
It works.