If you would like to know how many solutions does the system of two equations have, you can calculate this using the following steps:
x = -4y + 4 ... x + 4y = 4 /*(2)
2x + 8y = 8
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2x + 8y = 8
2x + 8y = 8
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0 = 0
The correct result would be infinitely many solutions.