Question 1079983
 x - 4y = 16 7x + 4y = 16


Your system should appear more like this:
{{{system(x-4y=16,7x+4y=16)}}}



{{{system(y=x/4-4,y=-(7/4)x+4)}}}


The first equation has point (0,-4) and slope  {{{1/4}}};
The second equation has   (0,4) and slope  {{{-7/4}}}.


{{{graph(300,300,-3,9,-6,6,x/4-4,-7x/4+4)}}}