how many gallons y of a 50% solution must be mixed with x gallons of a 20% salt solution to produce 10 gallons of a 38% salt solution. set up with two equations
y = gallons of a 50% solution
x = gallons of a 20% solution
10 gallons are produced between the two solutions, which means you need to start with a total of 10 gallons.
.5y + .2x = .38(10)