Question

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

Answer 1

Joaquim Rate per hour = 1/7
Josiah Rate per hour = 1/t

1/7 + 1/x = 1/3
(same denominator & simplification) gives: t = 21/4 = 5.25 .
 Josiah needs 5.25 hours to clean alone 
(I really don't know why the answer is 5.3 . Can you pls check with the teacher?

Answer 2

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