SOLUTION: two numbers have a sum of 28. one number is 4 more than the other. find the numbers.

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Question 240719: two numbers have a sum of 28. one number is 4 more than the other. find the numbers.
Answer by Stitch(470) About Me  (Show Source):
You can put this solution on YOUR website!
Setup:
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Equation 1: X+%2B+Y+=+28
Equation 2: Y+=+X+%2B+4
Solution:
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Since we know that Y = X + 4, plug (X + 4) into equation 1 for Y
Equation 1: X+%2B+Y+=+28
X+%2B+%28X+%2B+4%29+=+28 Simplify
2X+%2B+4+=+28 Subtract 4 form both sides
2X+=+24 Divide both sided by 2
highlight%28X+=+12%29
Now plug 12 in for X into equation 2
Equation 2: Y+=+X+%2B+4
Y+=+12+%2B+4
highlight%28Y+=+16%29
Checking the answer:
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Now go back to equation 1 and plug in 12 for X and plug 16 in for Y
Equation 1: X+%2B+Y+=+28
12+%2B+16+=+28
12+=+12