4-1

3

If you meant something else by "4-1" (for example, Chapter 4, Section 1 from a textbook, or problem 4-1 in an assignment), please tell me the subject and the exact problem statement or book you're using. I can then give a step-by-step solution, explain the underlying concept, or provide practice problems.

If you just wanted the arithmetic: 4 minus 1 equals 3.