Atruck traveled 60 km per hour the first hour, 45 miles per hour as the next 30 minutes and 50 km per hour in next 45 minutes what is the approximate distance the truck travel

 
134 kilometers or 83 miles.

Explanation: 
First make all the units equivalent, so 
60 km/h = 60 km/h or 37.28 m/h
45 m/h = 72.42 km/h or 45 m/h
50 km/h = 50 km/h or 31.07 
So in one hour the car has gone 60 km or 37.28 m because they travel at 60km/h, which means they get that far in that amount of time. 
In half an hour they get half of 45 miles, because 45 m/h means they get 45 miles in 60 minutes, so in 30 minutes, or half and hour, they are getting half of 45 = 22.5 miles or 36.21 kilometers. 
In 45 minutes they are getting 75% of 50 km because 45 minutes is 75% of an hour. So 75% of 50 is 37.5 km or 23.3 miles. 

Add this all together and get:
Kilometers:
60 + 36.21 + 37.5 = 133.71 km
Miles:
37.28 + 22.5 + 23.3 = 83.08 m 
133.71 km = 83.08 So it checks out.
This is approximately 134 km or 83 miles.