Answer:
The answer to your question is 2 or (2, 0)
Explanation:
Data
slope = m = 4
y-intercept = -8
Process
1.- Write the equation of the line in the slope y-intercept
 y = mx + b
In this equation:
m = slope
b = y-intercept
-Substitution
 y = 4x - 8
2.- To find the x-intercept, consider that y = 0 and solve for x.
 0 = 4x - 8
 4x = 8
 x = 8/4
  x = 2 or (2, 0)