A person travels in a car for 450 km at an average speed of 30 km/h, then 360 km at 40 km/h and finally reaches to the destination by travelling 150 km at a speed of 50 km/h. Determine the average speed during the whole journey.

A

$$\frac{320}{9}$$ km/h

B

$$\frac{370}{9}$$ km/h

C

$$\frac{340}{9}$$ km/h

D

$$\frac{310}{9}$$ km/h