Balanced 6-holes in linearly separable bichromatic point sets

We consider an Erdős type question on k-holes (empty k-gons) in bichromatic point sets. For a bichromatic point set S=R∪B, a balanced 2k-hole in S is spanned by k points of R and k points of B. We show that if R and B are linearly separable and |R|=|B|=n, then the number of balanced 6-holes in S is at least .