As the only witch in town, Kasandra has a monopoly in the business of casting spells. Because she is able to read people's minds, she knows exactly the maximum amount each person is willing to pay for her services. The demand for spells in her town is q = 10 p/5 , the marginal cost to cast each spell is $5. How many spells would Kasandra cast if she is using all the information she has to get the maximum profit possible?