I am stuck on this question and can't seem to figure it out.

Question:

calculate the maximum magnesium ion concentration in an aqueous solution of 0.020 M barium hydroxide, Ba(OH)2. The Ksp for magnesium hydroxide, Mg(OH)2, is 1.2 x 10^-11 at 25 degrees Celsius.

Thanks

I am still having trouble with this question. Does anyone have any ideas?