How do I write the following problem in elimination , graphing, substitution, and matrix techniques? x=$20.00 and y=$45.00. You need to purchase 250 sets of dishes. There are two different designs. One costs $20.00 and the other design costs $45.00. You have $6800.00 to spend. How many of each design should you order? I have looked in my textbook and it just confuses me more.