Final answer:
To find the markup from cost to sale price, first determine the original price before a markdown of 20%, which is $568.75. Then, subtract the cost ($280) from the sale price ($455), resulting in a markup of $175.
Step-by-step explanation:
The student is asking how to find the markup from cost to sale price when an item costing $280 is sold for $455 after being marked down by 20%. To calculate the markup, first, we need to determine the original price before the markdown. Since the item was sold at $455 after a 20% markdown, we can represent the original price as 100% and the sale price as 80% (because 100% - 20% = 80%). To find the original price (100%), which we'll call O, we set up this equation: $455 = 80% of O. Now, we convert 80% to a decimal, which is 0.80, and solve for O: $455 = 0.80O. Divide both sides by 0.80 to find O: O = $455 / 0.80. O = $568.75.
Now that we have the original price, to find the markup from cost to sale price, subtract the cost ($280) from the sale price ($455): $455 - $280 = $175. Therefore, the markup from cost to sale price is $175.