SOLUTION: Together kim and chris sort recyclables in 2 hours and 55 minutes. Alone it takes kim 2 hours more than chris. How long does it take chris alone ?

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Question 412349: Together kim and chris sort recyclables in 2 hours and 55 minutes. Alone it takes kim 2 hours more than chris. How long does it take chris alone ?
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
Together kim and chris sort recyclables in 2 hours and 55 minutes. Alone it takes kim 2 hours more than chris. How long does it take chris alone ?
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let x=minutes Cris takes to complete the job working alone
then 1/x = Chris' minute work rate
x+120=minutes Kim takes to complete the job working alone
then 1/(x+120)= Kim's minute work rate
175 minutes it takes Cris and Kim working together to complete the job
then 1/175 Chris'and Kim's minute work rate working together
sum of individual work rates=work rate working together
(1/x)+1/(x+120)=1/175
LCD=x(x+120)(175)
175(x+120)+175x=x(x+120)
175x+21000+175x=x^2+120x
x^2-230x-21000=0
factor or use quadratic formula to solve:
(x-300)(x+70)=0
x-300=0
x=300 minutes
x+70=0
x=-70 (reject)
ans: It would take Chris 300 minutes to do the job alone