You are almost right, you just forgot to put the x in. It should be -1/2x instead of just 1/2.
Answer: y = -x/2 + 5/2 or -1/2 x + 5/2 or 5/2 - x/2
x + 2y = 5
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Subtract x from both sides :
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x + 2y - x = 5 - x
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Combine like terms:
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2y = 5 - x
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Divide by 2 through:
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2y ÷ 2 = (5 ÷ 2) - (x ÷ 2)
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Simplify :
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y = 5/2 - x/2
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Answer: y = 5/2 - x/2
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