Adam's art gallery bought a photograph for $250 wholesale and marked it up 40%. What is the amount of the mark-up?

1. Change 40% to a decimal: 0.40. 2. Multiply the decimal by the wholesale price: 0.40 x 250. 3. This gives 100. 4. So the amount of mark-up is $100. _Source: OpenStax Prealgebra (CC BY 4.0), Ch 6 "Percents", section 6.3 Solve Sales Tax, Commission, and Discount Applications_