SOLUTION: The sum of two numbers is 42. One number plus 2 times the other number is 57. What are the numbers? The sum of two numbers is 45. Their difference is 9. What are the numbers?

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Question 108520: The sum of two numbers is 42. One number plus 2 times the other number is 57. What are the numbers?
The sum of two numbers is 45. Their difference is 9. What are the numbers?

Answer by elima(1433) About Me  (Show Source):
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The sum of two numbers is 42. One number plus 2 times the other number is 57. What are the numbers?
x+y=42
x+2y=57
Lets solve by elimination;
so we will multiply the first equation by -1;
(-1)x+y=42
-x-y=-42
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Now we will add that equation to the second;
cross%28-x%29-y=-42
cross%28x%29%2B2y=57
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y=15
now plug that into either original equation to find x;
x+15=42
x=27
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The sum of two numbers is 45. Their difference is 9. What are the numbers?
x+y=45
x-y=9
Since one variable will already be eliminated we will not need to multiply anything;
x%2Bcross%28y%29=45
x-cross%28y%29=9
_____________
2x=54
x=27
plug that into either equation for x;
27+y=45
y=45-27
y=18
:)
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