my problem involves creating a graph of log10(a) vs log10(P) and to calculate the mass of jupiter from the graph. I have created the graph and it seems to be right since the of the trend line is 3/2. My problem is that I am unsure how to go about calculating the mass from the graph. I used the orbital period and length of the semi-major axis of the Galilean satellites and 3 others to get the equation y = 1.5012x - 8.1973 I have tried using m1+m2= (4*P^2*a^3)/(G*P^2), though that produced a rather large value and doesn't utilize the graph at all. Any help or nudges in the right direction would be greatly appreciated, Thanks!