Based on the source text about lithium having 3 protons and losing 1 electron when it forms ions, how many electrons are in a lithium ion?

What the source text is telling you

You are given two key facts: lithium has 3 protons, and when lithium forms ions it loses 1 electron. The neutron count does not affect the number of electrons.

Electrons in a neutral lithium atom

For a neutral atom, the number of electrons equals the number of protons.

So neutral lithium has: $$e^- = p^+ = 3$$

Adjusting for ion formation

The source says lithium loses 1 electron when it forms ions: $$3 - 1 = 2$$

So the lithium ion (a $Li^+$ ion) has 2 electrons.