Thanks for the help

In one country, a monopolist takes over the production of Pfizer and J&J vaccines and begins selling vaccines to locals. To become fully immunized, some people prefer two shots of the Pfizer vaccine, while others prefer a single shot of the J&J vaccine. Nobody needs both vaccines for immunization. The demand for (2 dozes) of the Pfizer vaccine is Opf= 30-6p, and the demand for a single doze of the J&J vaccine is Qij= 40-4p. Assume that the marginal cost of producing one dose of either vaccine is MC= 1. The demand quantities Opf and Qii are expressed in millions of dozes, while the prices P and MC are expressed in the currency of the country. (a) Suppose, the price of one shot of a vaccine is P= 8. What is the market demand for immunization? (b) Suppose, the price of one shot of a vaccine is P= 3. What is the market demand for immunization