Question 616816
two numbers whose sum is 21 and whose difference is 5. let x be the first number and y be the second number. and solve for x and y how would i go about solving the question?
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Let x = one number
and y = second number
then from "two numbers whose sum is 21" we have
x+y = 21 (equation 1)
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from: "and whose difference is 5"
x-y = 5 (equation 2)
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Using the "addition method" combine both equations:
x+y = 21
x-y = 5
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2x  = 26
x = 13
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Second number, substitute above into:
x+y = 21
13+y = 21
y = 21-13
y = 8
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Answer: 8 and 13