Task: Question Answering
Input (English): Problem: a and b are 90 km apart they start to move each other simultaneously a at speed 10 and b at 5 km / hr if every hour they double their speed what is distance that a pass until he meet b ? 
Options: a ) 30 km , b ) 40 km , c ) 50 km , d ) 60 km , e ) 70 km
Output (English): d