Question

Jeremy is making a trail mix containing raisins and peanuts. Raisins cost $1.50 per pound. Peanuts cost $2.50 per pound. Jeremy spends $10.50 to make 5 pounds of trail mix. He uses the table below to organize this information.

A Table titled Trail Mix showing Pounds, Cost, and Total. The first row shows Raisins, with r, 150, and 1.5 r. The second row shows Peanuts, with 5 minus r, 2.50, and 2.5 left-parenthesis 5 minus r right parenthesis. The last row shows Mixture, with 5, blank, and 10.50.

Which equation can Jeremy use to determine the amount of raisins in the trail mix?

r + 1.50 = 1.5r
r + (5 – r) = 5
1.5r + 2.5(5 – r) = 10.50
1.5r + 2.5(5 – r) = 5

Answer 1

Third one: 1.5r + 2.5(5 − r) = 10.50.

Explanation: 1.5r is the cost of r pounds of raisins, 2.5(5 − r) is the cost of the peanuts, and their sum equals the total $10.50. Solving: 1.5r + 12.5 − 2.5r = 10.5 → −r = −2 → r = 2 (pounds of raisins).