In: Economics
a. If both salons choose prices simaltaneously, both firms will choose a price of 35$ such that they could serve their half of the street. (Customer is willing to pay 40$ at home and 5$ per mile for travelling, thus a customer upto half a mile away would be willing to pay 35$+2.5$+2.5$ for travelling) (They could each charge 30$ so that all consumers can afford it but even then only 500 customers will come to their salon as they will visit the one closer and therefore their profit will be less)
Thus the equilibrium prices are 35$ for both salons
Equilibrium profits=500*35$-500*5$=15,000$ for salon A
=500*35$-500*10$=12,500$ for salon B
Yes, these salons serve all customers(500 each)
b. if salon A's unit cost is $a, the value of a such that not all customers are served is a>35
If the unit cost of salon A is greater than 35, the customer half a mile away would have to pay 35+2.5+2.5=40$ for cutting at salon A, however if a is greater than 35,the customer will not be willing to pay more than 40$ and thus will not be served.
Hope it helps. Do ask for any clarifications required,