In order for the bookstore to continue its business, it should sell at least 15 books to meet its $75 cost. For the computation:The formula for solving the breakeven point (BEP) is:Fixed Cost / (Selling Price - Variable Cost) = BEPFixed Cost is the cost that remains constant whether the services provided or products sold increases or decreases.Variable Cost is the cost that varies or differs in proportion to the products or services produced, whether they increased or decreased. In the problem, the Fixed cost is 75 and the variable cost is 11, and lastly, the selling price is 16.To substitute the given to the problem:75 / (16 - 11) = 15