Xeller Company makes electronic keyboards. The practice model price is 220 and variable expenses are 190. The deluxe model price is 340 and the variable expenses are 250. The professional model price is 1,200 and the variable expense per unit is 800. Total fixed expenses are 187,000. Generally, Xeller sells 6 practice models and 3 deluxe models for every professional model sold.What is the number of professional models sold at breakeven?