Question 135393
The problem is: 
y=x-3 
x+y=5
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You are told that y = x-3 so substitute that into the 2nd equation
to get:
x+(x-3) = 5
2x-3=5
2x = 8
x = 4
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Now, since y = x-3, substitute to get:
y = 4-3 = 1
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Solution: (4,1)
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Cheers,
Stan H.