Should liters go on the top or the bottom of a conversion factor?

What's with the "or" in between conversion factors? Both conversion factors are equal to 1. However, we want to show that you can write conversion factors two ways—the base unit can be written on the top or bottom as long as the conversion factor is equivalent to 1 in the end.

Explanation:

answer a fan shaped mass of sediment deposited at the base of a mountain front do to an abrupt change in stream gradient;