The task is to generate the correct answer for a given math problem.
--------
Question: Problem: a man can row 6 kmph in still water . when the river is running at 3 kmph , it takes him 1 hour to row to a place and black . what is the total distance traveled by the man ?

Answer: 4.5

Question: Problem: a father said to his son , ' ' i was as old as you are at the present at the time of your birth ' ' . if the father ' s age is 52 years now , the son ' s age 5 years back was :

Answer: d ) 21

Question: Problem: if henry were to add 9 gallons of water to a tank that is already 3 / 4 full of water , the tank would be 7 / 8 full . how many gallons of water would the tank hold if it were full ?

Answer:
72