STAAR Algebra 1 Systems of Equations

Two customers went to a post office to buy postcards and large envelopes. Each postcard costs the same amount, and each large envelope costs the same amount.

•The first customer paid $12 for 14 postcards and 5 large envelopes.

•The second customer paid $24.80 for 10 postcards and 15 large envelopes.

What was the cost in dollars of each postcard?

• $1.42

• $0.35

• $1.15

• $0.63

• A

• B

• C

• D

Two customers went to a post office to buy postcards and large envelopes. Each postcard costs the same amount, and each large envelope costs the same amount.

•The first customer paid $12 for 14 postcards and 5 large envelopes.

•The second customer paid $24.80 for 10 postcards and 15 large envelopes.

What was the cost in dollars of each large envelope?

• $1.42

• $0.35

• $1.15

• $0.63

There are 15 plates in a kitchen cabinet. The diameter of each plate is either 7 inches or 12 inches. The diameter of all 15 plates combined is 140 inches.

Which system of equations can be used to find the number of 7-inch plates, x, and the number of 12-inch plates, y, that are in the cabinet?