Problema Solution
Facts:
Joey can clean his room in 10 hours.
His mom can clean his room in 5 hours.
What time will Joey's room be clean if he starts cleaning at 1:00 and
his mom begins to help him at 2:00.
Answer provided by our tutors
in 1 hour the room complete by joey is 1/10
while in 1 hour his mom will complete1/5
now as joey cleans 1/10 of room in 1 hour and then his mother join
hence time required after mom join t
1/10+t*(1/5+1/10)=1
=> 3/10 t= 9/10
=>t= 3
hence total time is 3+1= 4hour