SOLUTION: Mary can paint a room in 5 hours. Working together Bob and Mary can paint the room in 3.5 hours. How much time would it take for Bob to paint the room himself?

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Mary can paint a room in 5 hours. Working together Bob and Mary can paint the room in 3.5 hours. How much time would it take for Bob to paint the room himself?      Log On


   

Question 1103277: Mary can paint a room in 5 hours. Working together Bob and Mary can paint the room in 3.5 hours. How much time would it take for Bob to paint the room himself?
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
Rate x Time = Output
.
.
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R%5BM%5D%2A5=1
R%5BM%5D=1%2F5
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.
.
Together,
%28R%5BM%5D%2BR%5BB%5D%29%2A%287%2F2%29=1
R%5BM%5D%2BR%5BB%5D=2%2F7
Substituting from above,
R%5BB%5D=2%2F7-1%2F5
R%5BB%5D=10%2F35-7%2F35
R%5BB%5D=3%2F35
So,
R%5BB%5D%2At%5BB%5D=1
%283%2F35%29%2At%5BB%5D=1
t%5BB%5D=35%2F3
t%5BB%5D=11%262%2F3
11 hours 40 minutes