Posted by Eric on .
A lab technician has a 15 percent alcohol solution and a 35 percent alcohol solution. She wants to make 100 gallons of a 29 percent alcohol solution. How much of the 15 percent solution should she use?

Algebra 1 
Marth,
Start by defining variables.
Let x = the amount of the 15% alcohol solution.
Let y = the amount of the 35% alcohol solution.
We want to find x.
Now define equations from the word problems.
x+y = 100 to have 100 gallons of solution.
0.15x + 0.35y = 29 to have a 29% solution.
Solve the system of equations. x=?