Formulate the following IP problems, and solve them by Excel Solver.

$1.$ Orange Computer owns four production plants at which personal computers are produced. Orange

Computer can sell up to $20000$ computers per year at a price of $$3500$ per computer. For each plant,

the production capacity, the production cost per computer, and the fixed cost of operating a plant for a

year are given in the table below. Determine how Orange Computer can maximize its yearly profit

form computer production.