(d) Given, a car starts with speed of 2 0 km/h.
So. the car covers a distance of 20 km in one hour.
The speed of car increases after every hour.
Distance travelled by car A in 7h
= 20 + 30 + 40 + 50 + 60 + 70 + 80 = 350
Distance travelled by car 8 in 7h
= 50 + 50 + 50 + 50 + 50 + 50 + 50 = 350
So, both the car travel equal distance in 7 h.
Hence, option (d) is correct.