Hamburger costs $1.50 per pound and soy costs $1.00 per pound. The school cafeteria uses 50 more pounds of soy than hamburger and spends $350 a week. How much soy does the school use?

Suppose the the school uses x pounds of Hamburger, then the number of pounds of soy is x+50, the cost of Hamburger is 1.50x, the cost of soy is 1.00 (x+50), the total cost if 350

1.50x + 1.00 (x+50) = 350

2.50x+50=350

2.50x=300

x=120

120+50=170

so the school uses 120 pounds of Hamburger and 170 pounds of soy