Answers

2014-09-04T20:51:28+08:00
X + 2y = 4
2y = 4 - x
y = 2 - x

2x + y = 4
2x + 2 - x = 4
2x - x = 4-2
x=2

y = 2 - x
y = 2 - 2
y = 0

2x + y = 4
2(2) + 0 = 4
4 + 0 = 4
4=4
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