This is pretty basic algebra. This is G times m1 time m2 divided by d^2. (Note that should be d^2, not d2). In order to solve for m1, you must move G, m2, and d^2 to the other side of the = sign. In order to do this, we have to cancel them out of the side on which they are. To do this, you need to use the opposite function compared to the ones that are expressed in the original equation. You need to do this with each variable that is to be moved to both sides of the equation. Let me give you an example with a different equation. Let us consider x = ab/c^2. We want to solve this for b. We are multiplying by a. So, in order to move a, we mush divide both sides by a. That gives us x/a = ab/(ac^2) The a's above and below the slash on the right side of the equation cancel each other out giving us x/a = b/c^2 Now, we are still dividing b by c^2. So, in order to move that, we have to multiply both sides by c^2 getting xc^2/a = bc^2/c^2 Once again, the c^2's above and below the slash on the right cancel each other out giving us our final equation, xc^2/a = b Now, if you will apply this model to your equation and post your answer as a comment here, then I will tell you if you have it correct and perhaps give you some more help.

m1 = Fd^2/Gm2