Calculating Charges on Uniformly Charged Spheres

[simple_kuri]

Homework Statement

Suppose that the magnitude of the charge on the yellow sphere is determined to be 2q. Calculate the charge q_red on the red sphere.
Express your answer in terms of q , d_1 , d_2 , theta and .

Hi Guys iv done the first two bits to this problem
the sign of the charge on the yellow sphere is negative and the sign of the charge on the red sphere is positive.

I can't do this third part though.
It would be gr8 if you could help me out.

I don't know where to start.

 

[CompuChip]

Did you forget to tell us anything? Like the charge of the blue sphere (I would expect it to be q, but you didn't say that). Also, the charge on the red sphere could be anything. You need some more information to determine it, like the red sphere is stationary or is at a minimum of the electric potential.

Please state the entire problem.

 

[simple_kuri]

Thank u for the reply.
I was actually missing out that information which is why i got stuck on it.
I should have checked the notes they had given with the question.