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Last week, a candle store received $355.60 for selling 20 candles . Small candle sell for $10.98 and large candle sell for $27.98 . How many large candles did the store sell

 Dec 29, 2015
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Last week, a candle store received $355.60 for selling 20 candles . Small candle sell for $10.98 and large candle sell for $27.98 . How many large candles did the store sell

 

Let the small candles=c

Let the large candles=C, then we have:

c + C=20

10.98c + 27.98C=355.60

 

Solve the following system:
{10.98 c+27.98 C = 355.6
c+C = 20

In the second equation, look to solve for C:
{10.98 c+27.98 C = 355.6
c+C = 20

Subtract c from both sides:
{10.98 c+27.98 C = 355.6
C = 20-c

Substitute C = 20-c into the first equation:
{27.98 (20-c)+10.98 c = 355.6
C = 20-c

27.98 (20-c)+10.98 c = 10.98 c+(559.6-27.98 c) = 559.6-17. c:
{559.6-17. c = 355.6
C = 20-c

In the first equation, look to solve for c:
{559.6-17. c = 355.6
C = 20-c

559.6-17. c = 2798/5-17 c and 355.6 = 1778/5:
2798/5-17 c = 1778/5

Subtract 2798/5 from both sides:
{-17 c = -204
C = 20-c

Divide both sides by -17:
{c = 12
C = 20-c

Substitute c = 12 into the second equation:
Answer: | c=12     and     C=8
 

 Dec 29, 2015

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