Done!

_____________________________________

Number of posts =

Number of candidates =

Assume that .

A voter can vote to candidates,

---- (A)

----(B)

Rewriting LHS of (B) in reverse order and noting that,

--------------------------------

--------------------------------

---- (C)

Also note that,

+

Note that 1st box bracket = 1

2nd box bracket = 1980 ---- {from (A)}

3rd box bracket = 66 ---- {from (B)}

4th box bracket = 1

Now solving (A) & (B) with , we find that,