Can you form an angle bisector hen the angle is a straight line?

Yes. Angle bisector means where after splitting the angle the 2 angles formed has the same size.
Therfore when you construct an angle bisector on a straight line, both new angles would be 90°, and the angle bisector is just right in the middle.

750 miles. i'll create two functions a(m) for plan a, and b(m) for plan b. since plan a has a flat fee, plus a mileage fee, the function is: a(m) = 75 + 0.20m since plan b only has a mileage fee, it's function is: b(m) = 0.30m since we're looking for some mileage where both plans cost the same, let's set them equal to each other, then solve for m. so 75 + 0.20m = 0.30m 75 = 0.10m 750 = m so the rental fee for both plans will be equal at 750 miles.