Selling Price after a 80% Markup is applied to an item that Cost $5

Given: Cost = $5,  Markup = 80%
Markup as a Decimal: 80% = 0.8
Formula:
Selling Price = Cost * (1 + Markup as a Decimal)
Selling Price = $5 * (1 + 0.8)
Selling Price = $5 * 1.8
Selling Price = $9
Notes:
Markup Amount = Selling Price – Cost = $9 – $5 = $4
Profit = Markup Amount = $4
Profit Margin =   =   = 0.4444 = 44.44%