Answer:
1. Break even points in units will be = 2,700 units
2. Break-even point in dollar sales = $56,700
3. In case fixed expense increase by $600 then Break even point in unit sales = 2,900 units
Explanation:
Break even point = 
Fixed Cost = $8,100
Contribution per unit = Sale Price - Variable Cost = $21 - $18 = $3
1. Break even points in units will be
= 
2. Break-even point in dollar sales
= Break even point in units X Sale price per unit
= 2,700 units X $21 = $56,700
3. In case fixed expense increase by $600 then Break even point in unit sales
=
= 2,900 units
Final Answer
1. Break even points in units will be = 2,700 units
2. Break-even point in dollar sales = $56,700
3. In case fixed expense increase by $600 then Break even point in unit sales = 2,900 units