Order of buttons when on the right of the page

I've been going through various posts on this board to clarify my doubts but I haven't found anything yet.

As I understand, there are 3 methods of positioning buttons,

  1. by importance of the action.
  2. by how destructive the action could be.
  3. by frequency of use.

I'm currently working on a layout for a job portal in which I wish to have the Edit, Clone and End job actions on the top right of the form. The dilemma I'm facing is in which order these buttons should be placed in.

a. Left to Right Left to right

b. Right to Left Right to Left

I also saw this post, however there is no reasoning why Approve is on the right side in all 4 options.

Any articles or books where this is documented would be great.

Thanks!