Task duration based on units in task and resource capacity for uni

[Blathering1]

Need to complete 500 tasks. Each task is unit driven with varying number of
units. (eg a task requires 10 units to be build before it is completed).

I have 8 resource teams. Each team can build a different # of units per
hour. Duration of each task depends on the assignment of teams to a task.

I cannot seem to designate a number of units (items to build) to a task, and
a units per hour rate to a resource so the duration adjusts to the resource
capacity. In sense-- I need to add in a formula to calculate duration.

Any advice?