Joaquin can clean the house in 7 hours by himself. When joaquin and josiah work together it takes 3 hours. About how long would it take josiah to clean the house by himself

A) 6.3 hours

B) 5.8 hours

C) 4.0 hours

D) 5.3 hours

The answer would be C, because if it takes Joaquin 7 hours by himself and only 3 hours with Josiah that would mean that it takes Josiah 4 hours if he was working by himself. if you add up the sum of both of their work 3hrs+4hrs = 7hrs