Task: Question Answering
Input (English): Problem: the distance from city a to city b is 120 miles . while driving from city a to city b , cara drives at a constant speed of 30 miles per hour . dan leaves city a 90 minutes after cara . what is the minimum constant speed in miles per hour that dan must exceed in order to arrive in city b before cara ? 
Options: a ) 42 , b ) 44 , c ) 46 , d ) 48 , e ) 50
Output (English): d