Question 45019
Rearrange {{{ x-y=4}}} to give the equation of a line on the form "y=mx+c":
{{{y=x-4}}}
Now plot this line and you should notice that only 2 sets of the coordinates given is on that line:
{{{ graph( 300, 200, -6, 5, -10, 10, x-4) }}} 
Thhose coordinates are:
(0, -4) and (-3, -7)
I hope this helps.
P.S. I am trying to start up my own homework help website. I would be extremely grateful if you would e-mail me some feedback on the help you received to adam.chapman@student.manchester.ac.uk
Adam