I am struggling to transpose my OWN formula, my math skills are terrible. I have:

I know x is 5 because I made this problem. How do I reverse it and make x the subject?

I've been trying to work with the PIN example which generally makes sense:

P=I/N

I=P*N

N=N*I is this right?

What is the best way to remember this? How do you think about this in your head? Why are percentages so easy but this seems to confuse the hell out of me?

Sam