What mathematical equation do I use relating to normal approximation to the binomial?

I need to figure out what equation to start with to figure out this statistics problem. The question has multiple parts to it but I think if I can just figure out what equation to start with in parts a and b then I can figure out the rest for c, d, e and get the answers on my own.

An election with 10,000 votes had J defeating S by 9 votes.

a. How many votes did each candidate get?

b. If a total of 100 other votes weren’t counted, what is the smallest number of these votes that S would need to have won?

c. If P(S) = 50% what is the binomial probability that she got this minimum amount of votes.