Markup = $4 b) markup as a percentage of cost is 33.3% Step-by-step explanation: Markup markup = selling price - cost = $13 - 9 ... markup = $3 Markup as a Percentage of Cost To find the percent markup, divide the markup by the reference value and multiply the ratio by 100%. The reference value for markup is usually cost price, but sometimes may be selling price. ... markup / cost × 100% = 3/9×100% = 33 1/3% ≈ 33.3%