SOLUTION: Working together Jen and Dave can build a deck in 6 days. by himself Dave can do his job in 4 fewer days than Jen can by herself. what are some equations that represent this situat

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Question 1011449: Working together Jen and Dave can build a deck in 6 days. by himself Dave can do his job in 4 fewer days than Jen can by herself. what are some equations that represent this situation??

thanks for the help:)
Found 2 solutions by Boreal, ikleyn:
Answer by Boreal(15235)   (Show Source): You can put this solution on YOUR website!
Jen needs x days
Dave needs x-4 days
in 1 day, Jen does 1/x of the deck.
in 1 day, Dave does 1/(x-4) of the deck
in 1 day, working together, they can do 1/6 of the deck
(1/x)+(1/(x-4)=1/6
That's the equation.
Multiply everything by 6x(x-4)
6x-24+6x=x(x-4)
x^2-4x-12x+24=0
x^2-16x+24=0
x=(1/2) 16+/-(sqrt 256-96)
=(1/2)(16+/-sqrt 170
only the added makes sense (1/2)(29.03)=14.52 days
x-4=10.52 days for Dave
1/14.52=0.0689
1/10.52=0.0950
Their sum is 1/6 with rounding error.
Answer by ikleyn(52894)   (Show Source): You can put this solution on YOUR website!
.
Working together Jen and Dave can build a deck in 6 days. by himself Dave can do his job in 4 fewer days
than Jen can by herself. what are some equations that represent this situation?
---------------------------------------------------------------------- 
The system of two equations in two unknowns, d and j

 +  = ,

j - d = 4,

where d = # of days Dave can complete the job working himself, 
and   j = # of days Jen  can complete the job working alone.


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