Selling Price after a 80% Profit Margin is applied to an item that Cost $20

Given: Cost = $20,  Profit Margin = 80%
Profit Margin as a Decimal: 80% = 0.8
Formula:
Selling Price =  

Cost/ 1 – Profit Margin as a Decimal

Selling Price =  

$20/ 1 – 0.8

Selling Price =  

$20/ 0.2

Selling Price = $100
Notes:
Profit = Selling Price – Cost = $100 – $20 = $80
Markup Amount = Profit = $80
Markup Percentage =  

Markup Amount/ Cost

=  

$80/ $20

= 4 = 400%