SOLUTION: If x + 2y = 11 and 3x + y = 13, then find the value of (x + y).

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Question 252547: If x + 2y = 11 and 3x + y = 13, then find the value of (x + y).
Answer by drk(1908) About Me  (Show Source):
You can put this solution on YOUR website!
This is a system of linear equations. Usually, you can subtract down or use some kind of multiplication and get the answer directly. In this case, we cannot.
(i) 1x+%2B+2y+=+11
(ii) 3x+%2B+1y+=+13
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step 1 - multiply (ii) by -2.
(iii) +1x+%2B+2y+=++11
(iv) -6x+-+2y+=+-26
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step 2 - add down to eliminate the y.
(v) -5x+=+-15 - -> X = 3.
If X = 3, then y = 4 and (X + Y) = 7.