solve this for y first
subtract 5x from both sides
-y+3=-5x
subtract 3 from both sides
-y=-5x-3
multiply both sides by -1 to get rid of the - in front of the y
y=5x+3
This is now in slope intercept form. y=mx+b. In this form
m = slope
b = y intercept
y=5x+3
slope=5
y-intercept=3