We start out with the formula d=rt, where d is distance, r is rate (speed) and t is time. We know the time is the same for both vehicles, so we will solve this formula for t:
d=rt
Divide both sides by r: d/r = t
Since the time is the same, we will have a proportion in the form
d/r = d/r
The speed of the car is x, and it travels 150 miles. The speed of the plane is 150 faster than x, or x+150, and it travels 600 miles: