Question 865692
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
...
{{{1/x+1/(x+4)=1/1.5}}}
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