SOLUTION: Hi, I am having a hard time with setting up and solving this problem: Dal and Kim can assemble a swing set in 1.5 hr. Working alone, it takes Kim 4 hr longer than Dal to assemb

Question 865692: Hi, I am having a hard time with setting up and solving this problem:
Dal and Kim can assemble a swing set in 1.5 hr. Working alone, it takes Kim 4 hr longer than Dal to assemble the swing set. How long would it take Dal, working alone, to assemble the swing set?
Thank you for your help!
Answer by lwsshak3(11628) (Show Source): You can put this solution on YOUR website!
Dal and Kim can assemble a swing set in 1.5 hr. Working alone, it takes Kim 4 hr longer than Dal to assemble the swing set. How long would it take Dal, working alone, to assemble the swing set?
***
let x=time it takes Dal to assemble the swing set working alone.
1/x=his work rate
x+4=time it takes Dal to assemble the swing set working alone.
1/(x+4)=his work rate
1.5=time it takes Dal and Kim to assemble the swing set working together.
1/1.5=their work rate
sum of individual work rates=work rate working together
...

LCD:x(x+4)
x+4+x=x(x+4)/1.5
2x+4=(x^2+4x)/1.5
3x+6=x^2+4x
x^2+x-6=0
(x+3)(x-2)=0
x=-3 (reject, x>0)
or
x=2
How long would it take Dal, working alone, to assemble the swing set? 2 hrs

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