we are given 
For first 6 hours:
average speed is 44 mi/h
so, we can find distance travelled in first 6 hours 


For last 4 hours:
average speed is 50mi/h
so, we can find distance travelled in first 6 hours 


now, we can find total distance and total time 


total time is 4+6=10hours
now, we can find speed 

..............Answer