You can
put this solution on YOUR website!The question is asking "how many pounds of each should she buy?" That tells us what our variables should be.
x=pounds of peanuts
y=pounds of fancy nuts
x + y = 13 (equation 1)
3.50x + 7.50y = 85.50 (equation 2)
Solve this system of equations. I'll do it by substitution here.
From equation 1, y = 13 - x.
By substitution into equation 2, 3.50x + 7.50(13 - x) = 85.50
Solving for x we get x=3.
Substitute 3 for x into equation 1 to solve for y, and y=13.