Sabrina bought cookies and brownies for her party. She bought a total of 20 items. The cookies cost $1.50 each and the brownies cost $1 each. The total amount that she spent was $22.50. Write two equations to represent the situation. Use x for cookies and y for brownies.
Solve the equations and determine how many cookies and brownies she bought. Write the answer as an ordered pair. (x,y)