P = M/N is the original equation given to us. Multiply both sides by N and we end up with N*P = M. We multiply both sides by N to undo the division. Multiplication is the opposite of division.
The idea is to isolate N. In other words, get it all by itself on its own side. To do this, we undo the multiplication done to N. So we divide both sides by P
We will go from N*P = M to N = M/P
Answer: N = M/P
note: We know that the profit per magazine is P = 5.50, but we don't know how much money they want to raise (i.e., we don't know the value of M). This is why we can't find the actual numeric value for N.
