Answer and Explanation:
The computation is shown below;
The Variable cost is 
= 55% of $4 
=$2.2 
 Now 
Contribution margin per unit 
= Sale - Variable cost 
 = $4 - $2.2 
= $1.8 per unit 
 a.Breakeven point is 
= Fixed cost ÷ Contribution margin 
 In units 
= ($702,000 ÷ $1.8)
= 390,000 units 
 in dollars = (390,000 × $4)
= $1,560,000 
 b.Margin of safety = Total sales - Breakeven sales 
 In dollars = ($2,000,000 - $1,560,000)
= $440,000 
 Margin of safety ratio =Margin of safety ÷ Total sales 
 = ($440,000 ÷ $2,000,000)
= 22%