I need this solved with Excel and work shown if Microsoft Excel steps don't fully explain everything. If possible, please use Excel Solver plugin. If that doesn't work please use Microsoft Excel in some form to solve using reduced echelon form , system of equations and using Pivots.

Problem is...

The public library budgeted for fiction, nonfiction, and reference books as follows: Purchase 500 books each month at a total cost of $19,500. They purchased 50 more fiction than reference books. The average cost of fiction books is $30, of nonfiction is $40, and of reference is $50. (a) Find the number of books the library should buy in each category. (b) Because the library cannot buy a negative number of books, use the solution to find the maximum and minimum number in each category