Answer:
If Mark and Alexis work together on a particular truck, they can load all of the packages in 90 minutes.
Explanation:
Since Ali has hired Mark and Alexis to work for his shipping company, and Mark can load a truck with packages in 120 minutes, while Alexis can load the same number of packages in 240 minutes, to determine how long they can complete a truck between the two, the following calculation must be carried out:
((120 + 240) / 2) / 2 = X
(360/2) / 2 = X
180/2 = X
90 = X
So, if Mark and Alexis work together on a particular truck, they can load all of the packages in 90 minutes.