Selling Price after a 28% Markup is applied to an item that Cost $45

Given: Cost = $45,  Markup = 28%
Markup as a Decimal: 28% = 0.28
Formula:
Selling Price = Cost * (1 + Markup as a Decimal)
Selling Price = $45 * (1 + 0.28)
Selling Price = $45 * 1.28
Selling Price = $57.60
Notes:
Markup Amount = Selling Price – Cost = $57.60 – $45 = $12.60
Profit = Markup Amount = $12.60
Profit Margin =   =   = 0.2188 = 21.88%