Please show how to set up excel sheet before putting it into solver.

The operation manager of EasyCool Co$.,$ a manufacturer of air conditioners, is

now scheduling the production plan for the next four months. They will incur an

inventory cost for each unsold air conditioner at the end of every month. The

company now has $150$ air conditioners available and is required to hold at least

$80$ air conditioners at the end of month $4.$ Information for the next four months

is given as follows:

a$.$ Formulate an LP model for this problem.

b$.$ Construct an Excel Spreadsheet and use Solver to solve this problem.

What is the optimal production and inventory plan?

c$.$ What is the total cost of this plan?