How many pounds of the less expensive pears did Sally buy?

Question

sally bought two types of pears: one type cost $2.50 per pound other type cost $3.50 per pound. She bought a total of 10 pounds of pears. The total cost for both types of pears was $27.00. How many pounds of the less expensive pears did Sally buy?

Answer 1

x+y=10  pounds, so y=10-x

2.5*x +3.5*y=27$

2.5x +3.5*(10-x)=27

2.5x -3.5x +35=27

-x=27-35=-8

x=8

y=10-x=2