Transposing equations question, assitance!

hey guys i really need help completing my final transposing question and im not sure how to do it
:V=2R/R-r ; Make r the subject........ the ans is r=R(V-2) / V
Can anyone explain how to obtain this answer? thanks!

Sure. First multiply both sides by (R-r).

V(R-r) = 2R

Expand the left hand side.

VR - Vr = 2R

Subtract VR from both sides and take out a common factor of R.

-Vr = 2R - VR = R(2-V)

Now divide both sides by V multiply by -1.

r = -R(2-V)/V

Note that -(2-V) = (-2 + V) = V - 2.

r = R(V-2)/V.

Done!

V=2R/(R-r)
multiply by R-r on both sides on the eq.
V(R-r) = 2R
divide both sides by V
R-r = 2R/V
subtract R from both sides
-r = (2R/V) -R
-r = R(2/V -1)
-r = R(2-V)/V
multiply by -1 on both sides
r = R(V - 2)/V