Question bank / Systems of two linear equations in two variables

Math · AlgebraEasy

At a fundraiser, a club sold candles for $12\$12 each and bars of soap for $5\$5 each. The club sold 8585 items in all and collected $642\$642. If cc is the number of candles and ss is the number of bars of soap the club sold, which system of equations represents this situation?

A

c+s=642c + s = 642 and 12c+5s=8512c + 5s = 85

B

c+s=85c + s = 85 and 5c+12s=6425c + 12s = 642

C

c+s=85c + s = 85 and 12c+5s=64212c + 5s = 642

D

c+s=85c + s = 85 and c12+s5=642\frac{c}{12} + \frac{s}{5} = 642

Show answer and explanation

Answer: C

The total number of items gives c+s=85c + s = 85. The candles bring in 12c12c dollars and the soap brings in 5s5s dollars, so 12c+5s=64212c + 5s = 642.

Choice B attaches each price to the wrong item.

Why the other choices are wrong

  • A. This switches the totals. 85 is the number of items and 642 is the amount of money.
  • B. This pairs each price with the wrong item. Candles cost $12, so the candle term is 12c.
  • D. This divides the number of each item by its price. Money collected is the number sold times the price.
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