Task: Question Answering
Input (English): Problem: a car traveling at a certain constant speed takes 5 seconds longer to travel 1 km than it would take to travel 1 km at 75 km / hour . at what speed , in km / hr , is the car traveling ? 
Options: a ) 70 , b ) 72 , c ) 74 , d ) 75 , e ) 78
Output (English): a