A person can complete a journey in 9 hours. He covers the first one-third part of thejourney at the rate of 10 km/h and the remaining distance at the rate of 20 km/h. What is the total distance of his journey (in km)?

Correct option is B

Given:

Total time = 9 hours

First $$\frac{1}{3}$$​ of the journey at 10 km/h

Remaining $$\frac{2}{3}$$​ at 20 km/h

Formula Used: ​

Time = $$\frac{\text{Distance}}{\text{Speed}}$$ 

Solution:​

Let total distance = x km

Then:

Distance for first part = $$\frac{x}{3}$$​, speed = 10 km/h

Distance for remaining =$$\frac{2x}{3}$$​, speed = 20 km/h

Now, 

​$$\frac{x}{3 \times 10} + \frac{2x}{3 \times 20} = 9$$​​

​$$\frac{x}{30} + \frac{2x}{60} = 9$$​​

​$$\frac{2x + 2x}{60} = 9$$​​

​$$\frac{4x}{60} = 9$$​​

​$$\frac{x}{15} = 9$$​​

x = 135 km