Okay, here we have this:
Considering that the slope intercept form is the following:
y=mx+b
If we replace with the provided info we obtain the following:
8=m(1)+4
And here we can clear for the slope (m):
8=m(1)+4
8=m+4
m=8-4
m=4
With this slope we can replace in the slope intercept form and finally we obtain the following equation: