Question

Alex bought 10 potatoes and 6 onions for $15. Carlos bought 5 potatoes and 2 onions for $6. What is the cost of the onions?

Answer 1

Let $x=$ the cost of the onion, $y=$ the cost of the potatoe. Then

$$10x+6y=15$$

$$5x+2y=6$$

$$10x+6y-2(5x+2y)=15-2(6)$$

$$2y=3$$

$$y=1.50$$

The cost of the onions is $1.50 per unit.