Cost to Sales Price (Markup):

Profit Amount = Cost × Profit Margin
Sales Excluding VAT = Cost + Profit Amount
VAT Amount = Sales Excluding VAT × VAT Rate
Sales Including VAT = Sales Excluding VAT + VAT Amount

Sales Price to Cost (Margin):

Profit Amount = Sales Price × Profit Margin
Cost = Sales Price - Profit Amount
VAT Amount = Sales Price × VAT Rate
Sales Including VAT = Sales Price + VAT Amount

If Cost: $ 100, Profit: 25 %, VAT: 20 %:

Profit Amount = 100 × 0.25 = 25 $
Sales Excluding VAT = 100 + 25 = 125 $
VAT Amount = 125 × 0.20 = 25 $
Sales Including VAT = 125 + 25 = 150 $