Question 144931
 have to graph it.(the graphing method)
1) x + y = 1 3x + y = 7 
y = -x + 1
Plot two points:
Let x = 0, then y = 1
Let x = 1, then y = 0
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y = -3x + 7
Let x = 0, then y = 7
Let x = 1, then y = 4
{{{graph(400,300,-10,10,-10,10,-x+1,-3x+7)}}}
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2) 3x + 4y = 5 x - 2y = 5 
y = (-3/4)x + (5/4)
Plot two points:
Let x = 0, then y = (5/4)
Let x = 1, then y = (1/4)
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y = (1/2)x - (5/2)
Plot two points:
Let x = 0, then y = (5/2)
Let x = 1, then y = -2
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{{{graph(400,300,-10,10,-10,10,(-3/4)x+(5/4),(1/2)x -(5/2))}}}
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Cheers,
Stan H.