Answer:
$2,200,000
Explanation:
Margin of safety means by how much sales can fall before a firm starts making a loss.
Margin of safety  = Current Sales - Break even sales
where,
Break even sales = Fixed Cost ÷ Contribution margin ratio
               = $800,000 ÷ 0.40
               = $2,000,000
therefore,
Margin of safety  = $4,200,000 - $2,000,000
              = $2,200,000