SOLUTION: 10% disinfectant and 7% disinfectant solutions are combined to give 30 gallons of 8% disinfectant solution. How much of the 10% solution should be combined?

Question 805955: 10% disinfectant and 7% disinfectant solutions are combined to give 30 gallons of 8% disinfectant solution. How much of the 10% solution should be combined?
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Do it like this one. Only the numbers are different.
-----------
Amanda wants to make 8 gal. of a 20% saline solution by mixing together a 56% saline solution and a 8% saline solution. How much of each solution must she use?
================
e = amount of 8%
f = amount of 56%
---
e+ f = 8 (total solution)
8e + 56f = 20*8 (total saline)
---
e+ f = 8
e + 7f = 20
------------ Subtract
-6f = -12
f = 2
e = 6
RELATED QUESTIONS
A mixture of 8% disinfectant solution is to be made from 10% and 7% disinfectant... (answered by jim_thompson5910)

A mixture of 4% disinfectant solution is to be made from 8% and 3% disinfectant... (answered by josgarithmetic)

A mixture of 10% disinfectant solution is to be made from 11% and 7% disinfectant... (answered by josmiceli)

A mixture of 4% disinfectant solution is to be made from 7% and 2% disinfectant... (answered by addingup)

A mixture of 8% disinfectant solution is to be made from 12% and 5% disinfectant... (answered by ikleyn,greenestamps)

A mixture of 9% disinfectant solution is to be made from 12% and 7% disinfectant... (answered by jorel1380)

A mixture of 6% disinfectant solution is to be made from 7% and 3% disinfectant... (answered by Alan3354)

A mixture of 5% disinfectant solution is to be made from 7% and 4% disinfectant... (answered by stanbon)

A mixture of 6% disinfectant solution is to be made from 7% and 4% disinfectant... (answered by richwmiller)