We have that F is proportional to m1. Hence, we have that F=m1*c when we change the first mass. We also have that F=m2*c when we only change the 2nd mass. Since F scales inversely with the square of the distance, we have that [tex]F= \frac{c}{d^2} [/tex]. Combining all of the facts above, we get that F=c*[tex] \frac{m_1 m_2}{d^2} [/tex] where c is a constant.
