SOLUTION: Melanie can paint a barn by herself in x days. Her helper Melissa can paint the same barn by herself in 2x days. Write a rational expression for the fraction of the barn that the

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Question 311386: Melanie can paint a barn by herself in x days. Her helper Melissa can paint the same barn by herself in 2x days. Write a rational expression for the fraction of the barn that they complete in one day by working together. Evaluate the expression for x=5.
Found 2 solutions by mananth, josmiceli:
Answer by mananth(16949) About Me  (Show Source):
You can put this solution on YOUR website!
Melanie can paint a barn in x days
So she does 1/x of job in 1 day.
..
Melissa does it in 2x days.
so she does 1/2x of the job in 1 day.
..
Together they do 1/x + 1/2x of the job in 1 day
=3/2x of the job in 1 day.
if x =5
3/10 of the barn they will paint together in 1 day

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Add their rates of working to get their
rate working together
Melanie's rate:
(1 barn painted)/(x days)
Melissa's rate:
(1 barn painted)/(2x days)
---------------------
Let the fraction of the barn they paint working
together for 1 day = y
Their rate working together:
(y part of a barn painted)/(1 day)
1%2Fx+%2B+1%2F%282x%29+=+y%2F1
1%2Fx+%2B+1%2F%282x%29 is the fraction of the barn painted
working together
x+=+5
1%2F5+%2B+1%2F10+=+3%2F10
The paint 3/10 of the barn in 1 day