For every $106.67 you sell, $26.67 is profit and $80.00 covers your cost.
VAT adds $21.33 (20%) on top, so your customer pays $128.00 in total.
Your markup is 33.3%. Note: margin is measured against selling price, markup against cost, so markup is always higher than margin for the same transaction.
Next stepConsider running a sensitivity check: see how a 5% rise or fall in cost affects your gross price.