Question 571557
In three minutes a conveyor belt moves 800 pounds of recyclable aluminum from a delivery truck to a storage area. A smaller belt can move the same amount of cans the same distance in 9 minutes. If both belts are being used, how long will it take to move the cans to the storage area. 
-----------
The faster belt moves 800/3 pounds/min
The slower moves 800/9 pounds/min
-----
Add them, get the total pounds/min
Invert to get mins/pound
Multiply by 800
--------------------
800/3 + 800/9 = 2400/9 + 800/9 = 3200/9 pounds/minute
--> 9/3200 minutes/pound
*800 pounds = 7200/3200 minutes
= 9/4 minutes