What is operations that undo one another?

Answer 1

"Inverse operations"

An operation has an inverse if their effects cancel each other out.

X+Y-Y=X + and - are inverse

4+2-2=4

(A/B)xB=A x and / are inverse

(10/5)x5=10

Ythroot(X^Y)=X Ythroot and x^y are inverse

3rdroot(6^3)=6