SOLUTION: Tom and Jack are shingling a roof. Tom takes 75% of the time Jack does to shingle a roof. Together they finish the roof in 5 hours. A monkey comes along and pulls the shingles o

Algebra ->  Rate-of-work-word-problems -> SOLUTION: Tom and Jack are shingling a roof. Tom takes 75% of the time Jack does to shingle a roof. Together they finish the roof in 5 hours. A monkey comes along and pulls the shingles o      Log On


   

Question 545003: Tom and Jack are shingling a roof. Tom takes 75% of the time Jack does to shingle a roof. Together they finish the roof in 5 hours. A monkey comes along and pulls the shingles off in 9 hours. How long does it take Tom, Jack and the monkey to shingle one roof?
I tried 3/4t + t -1/9t = x
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Tom and Jack are shingling a roof.
Tom takes 75% of the time Jack does to shingle a roof.
Together they finish the roof in 5 hours.
A monkey comes along and pulls the shingles off in 9 hours.
How long does it take Tom, Jack and the monkey to shingle one roof?
:
let t = time required when all three are on the job
let the completed job = 1 (a shingled root)
we can replace Tom & jack with 5 hrs, a simple shared work equation then:
:
t%2F5 - t%2F9 = 1
multiply by 45 and we have
9t - 5t = 45
4t = 45
t = 45%2F5
t = 11.25 hrs. 11 hrs 15 min