Chapter 4 - Section 4.4 - Systems of Linear Equations and Problem Solving - Exercise Set - Page 322: 43

50 gallons of 30% solution, 100 gallons of 60% solution

30% solution (x) 60% solution (y) 50% solution (x+y) $.3x+.6y=.5*(x+y)$ $x+y=150$ $.3x+.6y=.5*(x+y)$ $.3x+.6y=.5x+.5y$ $-.2x+.1y=0$ $-.2x+.1y=0$ $10*(-.2x+.1y=0)$ $-2x+y=0$ $x+y=150$ $-2x+y=0$ $y=2x$ $x+y=150$ $x+2x=150$ $3x=150$ $3x/3=150/3$ $x=50$ $x+y=150$ $50+y=150$ $y=100$