SOLUTION: Andre and Eric have a home improvement business. They get a job to paint the living room of mrs. Jones. Andre can paint a room in 4 hours and Eric can paint a room in 12 hours. The

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Question 950897: Andre and Eric have a home improvement business. They get a job to paint the living room of mrs. Jones. Andre can paint a room in 4 hours and Eric can paint a room in 12 hours. They decide to paint a room together to save time. How long does it take for the two of them to paint the room?
Okay so far I got in an hour Andre can do the work in 1/4 the time and in a hour Eric can do 1/12 the time so I made and equation that x=the time to paint the living room and got the equation 1/4x+1/12x=1 so I found the lcd and got 3 hours but I think I have done this all wrong so can you please help me!!!
Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website!
Andre and Eric have a home improvement business.
They get a job to paint the living room of mrs. Jones.
Andre can paint a room in 4 hours and Eric can paint a room in 12 hours.
They decide to paint a room together to save time. How long does it take for the two of them to paint the room?
:
You are right, but here is an easy understandable way to do these "shared work" problems
let t = time required when they work together
let the completed job = 1 (a painted room)
:
Each will do a fraction of the job, the two fractions add up to
+ = 1
multiply equation by a common multiple of the denominator
12* + 12* = 12
Cancel the denominators
3t + t = 12
4t = 12
t = 12/4
t = 3 hrs when working together
:
:
See if the two fraction in fact add up to 1
+ =
+ = 1