The lines have equal gradients;
m

Equation of line 2;
y=mx+c
y=

x+c
-15=

+c
c=-11
y=4/5x-11
Is there a picture to go with it
The points (0, 3) and (4, -1) are on the graph of y = -x + 3.
I have a site that I use a lot that is perfect for problems like these. It's called Desmos.com. It's basically a free online graphing calculator that is super helpful for most problems relating to graphs.