Equation:
y - 10 = -5x
Solve:
(y - 10) + 10 = (-5x) + 10
y = -5x + 10
Remember the formula (Slope Intercept Form):
y = mx + b
m = Slope (Rise/Run)
b = Y-intercept
So your graph would look something like the attached image:
(Need further elaboration? Let me know!)