Question 48127
Before doing any substitutions, always solve for y.  Doing so yields {{{y=-expr(1/2)x+2}}} and {{{y=-expr(1/2)x-1}}}.  Because the slopes are exactly the same, that means the lines are parallel.  If you substitute 0 for x in both equations you get y=2 for the first equation and y=-1 for the second equation.  The graph is:
{{{graph(200,200,-5,5,-5,5,-x/2+2,-x/2-1)}}}