paralell to the line means has same slope
I happend to know that if you have 2 equations
ax+by=c and
dx+ey=f
if a=d and b=e, then the lines ar paralell
since it is paralell
the equation looks like this
7x+y=c
so
(1,-3)
(x,y)
sub those to find the c
7(1)+(-3)=c
7-3=c
4=c
the equation is 7x+y=4