sue, an experienced shipping clerk, can fill a ertain order 9 hours. Jim, a new clerk, needs 10 hours to do the same job. working together how long will it take them to fill the order?

Question

sue, an experienced shipping clerk, can fill a ertain order 9 hours.  Jim, a new clerk, needs 10 hours to do the same job.  working together how long will it take them to fill the order?

anonymous · Answer

$$\frac{  order }{ 9 hours } *x hours +\frac{  order }{ 10 hours } *xhours =1$$

or

$$\frac{ x }{ 9 } + \frac{ x }{ 10 } =1$$

anonymous · Answer

use method above, or go right to 

$$\frac{8\times 9}{8+9}$$ as a solution

anonymous · Answer

?

anonymous · Answer

why 8 and 9?

anonymous · Answer

because it is late an i am tired

anonymous · Answer

:)

anonymous · Answer

$$\frac{9\times 10}{9+10}$$ might work better
really if you do more than two of these style problems it is better to go right to the answer