Question

Joy needs to mix a 20% acid solution with a 60% acid solution to create 100 millileters of a 28% solution. How many millileters of each solution must Joy use?

Answer 1

Joy must use 80 milliliters of solution at 20% and 20 milliliters of solution at 60%

Explanation:

Let

x -----> milliliters of solution at 20%

y -----> milliliters of solution at 60%

we know that

`x+y=100` ----> equation A

`20\%=20/100=0.20`

`60\%=60/100=0.60`

`28\%=28/100=0.28`

so

`0.20x+0.60y=0.28(x+y)`

`0.20x+0.60y=0.28(100)`

`0.20x+0.60y=28` ----> equation B

Solve the system of equations by graphing

Remember that the solution of the system is the intersection point both graphs

The solution is the point (80,20)

see the attached figure

therefore

Joy must use 80 milliliters of solution at 20% and 20 milliliters of solution at 60%