Mark knows that the sales mix as a percentage of units sold is 20% for his hand-carved chess set and that it sells for $700. the sales mix as a percentage of units sold is 80% for his hand-carved backgammon set and it sells for $300. if mark knows that his company-wide break-even point is 4,200 units, how many chess sets and how many backgammon sets does he need to sell to break even