A store marks up an item that costs $40 by 30%. What is the selling price?

A markup is added to the cost. First find the markup: 30% of $40 = 0.30 × 40 = $12. Then add it to the cost: $40 + $12 = $52. Equivalently, a 30% markup means selling at 130% of cost: 1.30 × $40 = $52. Markup problems are the mirror image of discount problems — you add the percentage instead of subtracting it. The $12 distractor is just the markup amount, not the selling price. The item sells for $52.