Marginal cost is the additional cost imposed by the production of one additional item. Marginal benefit is the additional benefit of producing one additional item. For a certain company, the marginal cost C, in dollars, of you are currently producing n items, is given by C(n) = 5 + n, and the marginal benefit B, in dollars, is given by B(n) = 25 * 0.9ⁿ. Economic efficiency occurs at the production level marginal cost and marginal benefit are the same. What production level n gives economic efficiency for this company? (Round the function values to one decimal place.)