Question

insert one comma to separate the coordinate adjectives.
since the overwhelmed exhausted office manager at the insurance company couldnt balance her countless daily responsibilities, she began looking to hire an assistant.

Explanation:

Coordinate adjectives are adjectives that modify the same noun and can be separated by a comma (or "and"). Here, "overwhelmed" and "exhausted" both modify "office manager" and are coordinate adjectives, so a comma should be placed between them.

Answer:

Since the overwhelmed, exhausted office manager at the insurance company couldn't balance her countless daily responsibilities, she began looking to hire an assistant.