Question 177524
1.{{{4x+2y=8}}}
2.{{{y=-2x+4}}}
Substitute eq. 2 into eq. 1,
1.{{{4x+2y=8}}}
{{{4x+2(-2x+4)=8}}}
{{{4x-4x+8=8}}}
{{{8=8}}}
A result like this tells us that eq. 1 and eq. 2 are the same line. 
There are an infinite number of solutions, that is all the points on the line, {{{y=-2x+4}}} solve both eq. 1 and 2.