And show work.. a local auto part store purchases a set ofbrakes from a wholesaler for $55 and sells them to a customer for $93. what percent markup was charged?

Hi there! So the the new price is $93, and went up from $55. Let's subtract the numbers. 93 - 55 is 38. The change is 38. To find the percent markup, we can write and solve a proportion. Set it up like this:

38/55 = x/100

This is because the amount of change goes above the original (55), and x represents the percent out of 100. We are looking for the markup. Let's cross multiply the values. 100 * 38 is 3,800. 55 * x is 55x. 3,800 = 55x. Now, divide each side by 55 to isolate the x. 55x/55 cancels out. 3,800/55 is 69.0909 or 69 when rounded to the nearest whole number. There. The percent of markup is approx. 69%.