How to subtract two large polynomials by rewriting as an addition problem

The video tutorial explains how to simplify subtraction problems by rewriting them as addition problems. The teacher demonstrates distributing negative signs to each term, making subtraction easier. The importance of arranging terms in descending order and using the vertical method for addition is emphasized. The tutorial concludes with a final example, showing the complete process and the final answer.

Explain the significance of adding vertically in polynomial addition.

What is the final answer when combining the terms 15X^3, -5X^2, 5X, and -6?