A k-move is defined to be a local change in a knot projection that replaces two untwisted strings with two strings that twist around each other with $k$ crossings in a right-handed manner. A -k-move is the same with left-handed twists.
We say that two knots are k-equivalent if we get from one projection of a knot to a projection of the otherthrough a series of k-moves or -k-moves.
Now I need to prove that the three knots in the image below are 3-equivalent to a trivial link. I think that first k-move or -k-move on the trivial link would always result in trefoil. I couldn't proceed further.