I couldn't figure out how to rearrange so i looked at the answer but it still didnt help.
If V = 12R / (r + R) , then R =
Vr / (12 - V)
We have to rearrange the equation to make R the subject.
Start by cross multiplying by (r + R); V (r + R) = 12R
Multiply out the bracket Vr + VR = 12R
I pulled this off a website, I can't figure out how they get to Vr + VR=12R
but I cant figure out how to get from that to Vr/(12-V)