Question

Mr. Yi buys vegetables at a market. He purchases 6 pounds of potatoes, p, and 3 pounds of onions, n, for $18. Onions cost twice as much as potatoes. To determine the unit price for each item, his daughter sets up and solves the system of equations shown.

Answer 1

Unit price of potatoes = $1.50.

Unit price of onions - $3.

Explanation:

The system of equations is

6p + 3n = 18

n = 2p

Substitute n = 2p in the first equation:

6p + 3(2p) = 18

6p + 6p = 18

12p= 18

p = 18/12 = $1.50 .

Now plug p = 1.50 into the second equation:

n = 2*1.50 = $3.

Answer 2

6 pounds of potatoes = $9

3 pounds of onions = $9

The onions cost $3 per pound

and the potatoes cost $1.50 per pound

Explanation: