Answer:
about 36.1 miles per hour
Explanation:
The cars' distance from the starting point is proportional to time, since both started at the same time. 1 hour after they started, Car A is 30 miles north of the origin, and Car B is 20 miles west of the origin. The distance between them can be found using the Pythagorean theorem:
d = √(30² +20²) = √(900 +400) = 10√13 ≈ 36.056
The distance between the cars is increasing at the constant rate of about 36.1 miles per hour.