Task: Question Answering
Input (English): Problem: tom traveled the entire 100 miles trip . if he did the first 50 miles of at a constant rate 20 miles 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 ? 
Options: a ) 28.36 mph , b ) 26.55 mph , c ) 28.57 mph , d ) 25.56 mph , e ) 28.45 mph
Output (English): c