To start, we would want to know what variables we have and what they mean to us. For this, I'd use d for distance (west in miles) from the runway and h for height off the ground (in feet). Next we need to make a linear function to solve for d. To do this, we need a slope, which we could find by doing [tex]m= \frac{ d_{2} - d_{1} }{ h_{2} - h_{1} }[/tex] using your initial values as your 2 values. With this we get [tex]m= \frac{150-90}{25000-19000} = \frac{60}{6000} = \frac{1}{100}[/tex] or 0.01 as your slope. Now, using your first values and the point-slope form (and d for y, h for x), we get the equation d-150=0.01(h-25000) --> d-150=0.01h-250 --> d=0.01h-100 as your equation (you can plug in your known values to test). Lastly, we need the distance from the runway when the plane is at ground level, or at h=0. We plug that in and get -100. Seeing as this is in miles west of the runway, the negative tells us to swap our direction, so we get 100 miles east of the runway. This means our answer is the plane will be 100 miles east of the runway when it's at ground level.
