Question 987568
{{{2y = x + 1}}}
{{{2y-1 = x}}}

(((4y = 2 - 2x}}}
{{{4y - 2 = 2x}}}  plug in the value for x above
{{{4y - 2 = 2(2y - 1)}}}
{{{4y - 2 = 4y -2}}}

which is "true"
The two equations are for the same line.