Decision Models - excel spreadsheet, using SOLVER

need help with this question ASAP:

Suzzalo Library is planning to buy new copier machines. It has narrowed its selection to two different models: Model A, a high-speed copier, and Model B, a lower-speed but less expensive copier. Model A can handle 20,000 copies a day and costs $6,000. Model B can do 10,000 copies a day, but costs only $4,000. The Suzzalo staff wants to have at least six copiers to be able to space them throughout the library, and at least one high-speed copier in the library. Finally, the copiers purchased must have a collective capacity of at least 75,000 copies a day. The objective is to determine the mix models A and B that will handle these requirements at minimum cost.

a) Formulate this problem in algebraic form. That is, define the decision variables, and express the objective function and all constraints in terms of these decision variables.

b) Solve this problem using Solver.

c) In simple English, state your proposed solution and its cost.