SOLUTION: Kim can unload a delivery truck in 20 minutes and Rom can do it in 35 mins. If they work together, how long will it take?

Question 100038: Kim can unload a delivery truck in 20 minutes and Rom can do it in 35 mins. If they work together, how long will it take?
Answer by ptaylor(2198) (Show Source): You can put this solution on YOUR website!
Let t=time it takes both working together
Kim unloads at the rate of 1/20 delivery truck per minute
Rom unloads at the rate of 1/35 delivery truck per minute
Together, they unload at the rate of (1/20+1/35 or 11/140) delivery trucks per min
1/20+1/35= The LCM is 140. Multiply both sides by 140/140
7/140+4/140=11/140
So our equation to solve is:
(11/140)*t=140/140-------(note 140/140 denotes one delivery truck)
Multiply both sides by 140
11t=140 divide both sides by 11
t=12.73 min---------------------time it takes both working together
CK
(1/20)*12.73+(1/35)*12.73=1
0.636363+0.363636=1
~1=~1

Hope this helps---ptaylor

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