dx/dt = v. I hope you didn't multiply both sides by t and divide both sides by v to get the equation above. If that's what you did (just a guess), that's not a valid operation. dt is not the product of d and t.
these derivatives are trivial. you can easily learn to do them in a single day.
you would be better off learning to do this yourself than asking us to do it for you
They are, I was trying to show someone that they could do what I asked in the initial question with a different derivative, they were confused and I was struggling to justify that it was true, getting myself in a loop of confusion. I was not really asking people to do it for me.