Calendar / reverse and forward offsets: If three days after today will be Tuesday, what day was four days before yesterday?

Introduction / Context:
We solve for “today” first, then move backward from “yesterday.”

Given Data / Assumptions:
Today + 3 = Tuesday ⇒ Today = Saturday.

Concept / Approach:
Yesterday = Friday; four days before that is Monday.

Step-by-Step Solution:

Final Answer:
Monday