First, we can start with the equation of a line
y = mx + b
We are given the slope, m = 1/4. Plug this into our function
y = 1/4 x + b
Now we need to find b (y-intercept). We are given the x-intercept, where the line crosses the x-axis. So we know the value of y = 0 at the x-intercept. This point is (8,0). We can plug this value into our equation above (since we know this point is on the line) and solve for b.
0 = 1/4(8) + b
0 = 2 + b
b = -2
Plug this b value into the equation we were building for our final equation
y = 1/4 x - 2