Question 145905: Alexander bell is selling answering machines. he sells two types a tape maching that sells for $8 and a disgital for $20. if he sells a ttoal of 30 answering machines and his total receipts were $492, how many of each type of answering machine did he sell
Answer by nerdybill(7384)   (Show Source):
You can put this solution on YOUR website! Alexander bell is selling answering machines. he sells two types a tape maching that sells for $8 and a disgital for $20. if he sells a ttoal of 30 answering machines and his total receipts were $492, how many of each type of answering machine did he sell
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In algebra, assign variables to things you don't know. Then derive the necessary equations from the problem to solve it.
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Let t = number of tape machines sold
and d = number of digital machines sold
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Since there are two unknowns, we must derive two equations:
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Equation 1: "he sells a total of 30 answering machines" we get:
t + d = 30
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Equation 2: "total receipts were $492" and "a tape maching that sells for $8 and a disgital for $20" we get:
8t + 20d = 492
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Now we can solve:
t + d = 30
8t + 20d = 492
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Using the "substitution" method, solve equation 1 for t and plug it into equation 2:
t + d = 30
t = 30 - d
plugging it into equation 2:
8(30 - d) + 20d = 492
240 - 8d + 20d = 492
240 + 12d = 492
12d = 492-240
12d = 252
d = 21
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plug the above into equation 1 and solve for t:
t + d = 30
t + 21 = 30
t = 30 - 21
t = 9
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Sold 9 tape machines and
sold 21 digital machines
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