Start by solving for y to get this in y=mx+b form
subtract 5x from both sides
4y=-5x+4
divide by 4
y=4/5x+4/4
simplify to
y=4/5x+1
Now you know that the slope of the first line is 4/5
The slope of the second line is -4/5
so the second equation is
y=-4/5x+?
since the line has to cross the point -1,9 you can plot that point on the graph and then use the slope to find another point.
from the point -1,9 you can use rise over run to go down the graph 4 spots to 5 and to the right on the graph 5 spots to 4
your second point would be (4,5)
y=-4/5x+41/5 is the equation for the second line
connect those points to get your line. The two lines look like this: