TOM traveled the entire 100 miles trip. If he did the first 50 miles of at a constant rate 20miles per hour and the remaining trip of at a constant rate 50 miles per hour, what is the his average speed, in miles per hour?  Choose the correct choice.
A) 28.36 mph
B) 26.55 mph
C) 28.57 mph
D) 25.56 mph
E) 28.45 mph
avg speed = total distance/ total time = (d1+d2)/(t1+t2) = (50+50) / ((50/20)+(50/50)) = 60*2/3 = 28.57 mph   28.57 mph
<result>C</result>
TOM traveled the entire 100 miles trip. If he did the first 50 miles of at a constant rate 20miles per hour and the remaining trip of at a constant rate 50 miles per hour, what is the his average speed, in miles per hour?