# A discrete mathematics problem by Aira Thalca

6 different balls are to be placed in three different boxes A, B, C. Each ball is placed uniformly at random in one of these boxes. The probability that box A will contain exactly 3 balls can be written as $$\frac{a}{b}$$, where $$a$$ and $$b$$ are coprime positive integers. Find $$a+b$$.

×