A monopoly is considering selling several units of a homogeneous product as a single package. Analysts at your firm have determined that a typical consumer's demand for the product is Q^d = 70 0.25P, and the marginal cost of production is $100. a. Determine the optimal number of units to put in a package.

b. How much should the firm charge for this package?

I get 22.5 and $190, but "check my work" say's it's wrong... I rounded up to 23 and $188, and it was still wrong.