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