Question

a car covers a distance of 490 km with a speed of 70km and then covers a speed of 90km calculate its average speed

Answer 1

Average speed = total distance divided by total time.

In the first part, the car covered 490 km in 7 hours, but I think you mistyped the second part (“then covers a speed of 90km”) and a critical piece is missing to find the total distance and time.