Answer:
C) 55 miles per hour
Explanation:
In order to calculate this you just have to see how many miles did he traveled and then divided that by the minutes that he spent.
So in the first part of the trip he traveled 30 minutes at a speed of 64 miles, that makes up for 32 miles.
And in the second part of the trip he traveled for 48 minutes at 50 miles per hour, that makes for 40 miles
So he traveled 72 miles total, divided by 78 minutes=.923 miles per minute, we just multiply this by 60 and we have that he traveled at 55.38 miles per hour.