Part of chain link broken I just got this bike from a neighbor and I saw that one of the chain links is broken on one side but not the other. What's the cheapest way to fix this situation?

The bike is a Next Xelite that I'm looking to upgrade to an E-bike.
If one of the side plates of the chain is falling off, you need a new chain.

Chains are relatively cheap, and get one with a master link so you don't even need a special tool.

It may be possible to push it back on, but it'll fall off again real quick, probably taking the other side with it.  This is false economy.  You should also start a maintenance log of when various tasks were done, same as a car logbook.  Chains should be replaced periodically, before they chew into the cassette.