Sydney Marathon is organizing a charity marathon event to raise some funds. Their estimation of cost is as follows: Athletes souvenir: :$25 Lunch and drinks for players :$15 Council charge: $1400 Support staff payment: $1000 Sydney Marathon is planning to make the event free for the spectators. However, the participation fee is $100 for the athletes. Considering the above information, calculate the followings: 

a. Break-even quantity. 

b. Break-even sales. 

c. How many participants is required if Sydney Marathon is aiming to raise $5100