Mx = Nx - Pt
To isolate 'x', we have to group all terms that have 'x' together
We have Mx on the left-hand side of the equation and Nx on the right.
Moving Nx to the left-hand side of the equation, we have:
Mx - Nx = Pt
From here we factorize 'x'
x (M - N) = Pt
Then we divide both sides by (M-N)
