Quick Copies ordered 100 reams of paper for a total cost of $1255. Reams of white paper cost $11.50 each, and colored reams cost $13.00 each. Which of the following systems of linear equations can be used to determine w, the number of white reams of paper ordered, and c, the number of colored reams of paper ordered?

A. w + c = 100
    13w + 11.50c = 1255
Incorrect. The second equation means that the white paper is $13.00 and the colored paper is $11.50.

B. w - c = 100
    13w + 11.50c = 1255
Incorrect. The first equation should not be subtraction. The second equation means that the white paper is $13.00 and the colored paper is $11.50.

C. w + c = 100
    11.50w + 13c = 1255
Correct! These two equations match the problem.

D. w - c = 100
    11.50w + 13c = 1255
Incorrect. The first equation should not be subtraction.

A store sold a total of 436 large and small Silly Bandz during one day. Total Silly Bandz sales were $1119. Large packs of Silly Bandz sold for $3, and small packs of Silly Bandz sold for $1.50. Which system of linear equations can be used to find l, the number of large Silly Bandz sold, and s, the number of small Silly Bandz sold?

A. l + s = 1119
    3l + 1.50s = 436
Incorrect. The first equation means the store bought 1119 Silly Bandz.

B. l + s = 436
    3l + 1.50s = 1119
Correct! This answer matches the problem situation.

C. 1.50l + 3s = 436
    l + s = 1119
Incorrect. The first equation means the large Silly Bandz are $1.50 and the small are $3.00. The second equation means the store bought 1119 Silly Bandz.

D. l + s = 436
    1.50l + 3s = 436
Incorrect. The second equation means the large Silly Bandz are $1.50 and the small are $3.00.

Benton and Cantrice went to a store to buy earrings on sale for $5 each, tax included. Benton purchased two and a half times as many earrings as Cantrice purchased. Together they purchased 14 pairs of earrings. Which system of linear equations can be used to determine b, the number of pairs of earrings Benton purchased, and c, the number of pairs of earrings Cantrice purchased?

A. Incorrect.
The second sentence means Benton purchased half as many earrings as Cantrice.

B.
Incorrect. The first equation means Benton and Cantrice are $5.00, very wrong. The second sentence means Cantrice purchased half as many earrings as Benton.

C.
Correct! These two equations match the problem.

D.
Incorrect. The second sentence means Cantrice purchased two and a half times as many earrings as Benton.

Dario works at Ernie’s Electronics Store. Last week he sold 6 more than 3 times the number of MP3 players that he sold this week. Dario sold a total of 108 MP3 players over the 2 weeks. Which system of equations can be used to find l, the number of MP3 players he sold last week, and t, the number of MP3 players he sold this week?

A. l + t = 108
    t = 3l + 6
Incorrect. The second sentence means this week he sold 6 more than three times the number he sold last week.

B. l + t = 108
    t = 3l − 6
Incorrect. The second sentence means this week he sold 6 less than three times the number he sold last week.

C. l + t = 108
    t = 3l − 6
Incorrect. The second sentence means last week he sold 6 less than three times the number he sold this week.

D. l + t = 108
    t = 3l + 6
Correct ! This answer matches the problem situation.

The perimeter of a rectangular tray is 152 centimeters. The deck’s length, l, is 4 centimeters less than 3 times its width, w. Which system of linear equations can be used to determine the dimensions, in centimeters, of the tray? {Hint P = 2l + 2w}

A. 2l + 2w = 152
    l = 4 − 3w
Incorrect. The second equation is wrong because you need to change the order when you see the phrase less than.

B. 2l + 2w = 152
    l = 4w − 3
Incorrect. The second equation means 3 less than 4 times the width.

C. 2l + 2w = 152
    l = 3 − 4w
Incorrect. The second equation is wrong because you need to change the order when you see the phrase less than. Also, the 4 and 3 are in the wrong places.

D. 2l + 2w = 152
    l = 3w − 4
Correct! This answer matches the situation in the problem.