SOLUTION: ok, here we go. John and Harry can paint a house in 10 days. when working alone John can paint the house in 30 days. How many days will it take Harry to paint the house. I ha

Question 107977: ok, here we go.
John and Harry can paint a house in 10 days. when working alone John can paint the house in 30 days. How many days will it take Harry to paint the house.
I have no idea how to do this probolem.
Found 2 solutions by edjones, ankor@dixie-net.com:
Answer by edjones(8007) (Show Source): You can put this solution on YOUR website!
The trick is to invert things at first and turn them right side up at the end.
John can do 1/30 of the job in 1 day.
1/30+h=1/10
h=3/30-1/30
h=2/30=1/15 Harry can do 1/15 of the job in one day or the entire job in 15 days.
Ed
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
John and Harry can paint a house in 10 days. when working alone John can paint the house in 30 days. How many days will it take Harry to paint the house.
:
Here's a method you can use on all these kind of problems
:
Let the completed = 1, each will do a fraction that will add up to 1
It's obvious that John will complete 1/3 of the job in 10 days (10/30)
Therefore John has to do 2/3 of the job. What denominator of 10 = 2/3?
:
Let x = Harry's time by himself
:
+ = 1
:
Get rid of the denominators, multiply equation by 30x
:
30x* + 30x* = 30x(1)
:
Cancel out the denominators and you have;
10x + 30(10) = 30x
:
10x - 30x = -300
:
-20x = - 300
:
x = -300/-20
:
x = 15 days required by John by himself
:
:
Check the solution by adding up the fractions
+ =
+ = 1
:
Did this make sense to you? Any questions?
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