Two cars start from the same place at the same time at right angles to each other. Their speeds are 54 km/hr and 72 km/hr, respectively. After 20 seconds the distance between them will be:

Answer: Option D

54 km/h = 54 × $$\frac{5}{18}$$ = 15 m/s
72 km/h = 72 × $$\frac{5}{18}$$ = 20 m/s

The distance of BC = 15 × 20 = 300 m
The distance of AB = 20 × 20 = 400
$$\text{AC}=\sqrt{{400}^2+{300}^2}=500$$