SOLUTION: Nancy can paint a house twice as fast as Terry can. They year they worked together it took them 7 days. How long would it take each to paint the house alone?

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Question 110491: Nancy can paint a house twice as fast as Terry can. They year they worked together it took them 7 days. How long would it take each to paint the house alone?
Found 2 solutions by ptaylor, josmiceli:
Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
Let x=amount of time it takes Nancy to paint a house
Then 2x= amount of time it takes Terry to paint a house
Now Nancy can paint at the rate of 1/x houses per day
Terry can paint at the rate of 1/2x houses per day
Together they can paint at the rate of 1/7 house per day. So our equation to solve is:
(1/x)+(1/2x)=1/7 multiply each term by 14x
14+7=2x collect like terms
21=2x divide both sides by 2
x=10.5 days-------Amount of time it takes Nancy to paint a house
2x=2*10.5=21 days----Amount of time it takes Terry to paint a house
CK
(1/10.5)+1/21=1/7 multiply each term by 21
2+1=3
3=3
Also
10.5*2=21
21=21

Hope this helps-----ptaylor

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
N = nancy's time working alone
T = Terry's time working alone
%281%2FN%29+%2B+%281%2FT%29+=+1%2F7
N+=+2T
%281%2F%282T%29%29+%2B+%281%2FT%29+=+1%2F7
multiply both sides by %282T%29%28T%29%2A7
7T+%2B+14T+=+2T%5E2
2T%5E2+-+21T+=+0
T%282T+-+21%29+=+0
T = 0 is a solution, but disregard it
2T+=+21
T+=+10.5days Terry's time working alone
N+=+2T
N+=+21days Nancy's time working alone
check
%281%2FN%29+%2B+%281%2FT%29+=+1%2F7
%281%2F21%29+%2B+%281%2F10.5%29+=+1%2F7
%281%2F21%29+%2B+%282%2F21%29+=+3%2F21
OK