Quandaries and Queries Name: Chet Warfel Who is asking: Other Level: All Question: My salesman calculates a customers profit margin by dividing what the customer paid by what he sells for, then subtracting that answer from 1. For example a customer sells a product for \$15. He bought it for \$10. 15/10=.66 Subtract that from 1 and get a profit % of 33% Here's my question: If I want to figure what a reseller will sell a product for if he wants 40% margin(by the technique above), what formula do I use? Let's say I want to sell a product for 8.50, and I want the reseller to make 40% My best technique is "guess and check" by plugging in the numbers and seeing if I'm too high or too low, then trying again. If I just multiply by 1.4 ....well that doesn't work! Help! Thanks in advance. Chet Hi Chet, I like this question, it shows the power of some algebra. First there is a typo in the question, to get the 0.66 above you should have said 10/15. I need to introduce some letters to explain what to do. Suppose that the customer bought the item for \$b and he sold it for \$s. Your salesman calculates the profit margin (I will call it m) by m = 1 - b/s In your example b = 10, s = 15 and m = 1 - 10/15 = 1 - 2/3 = 1/3 and 1/3 is 33% Your question is then, if you know m and b, what is s? This is where you need some algebra. If m = 1 - b/s then  b/s = 1 - m and hence s = b/1 - m In the example you give m = 40% = 0.40 and b = \$8.50, so s = b/1 - m = 8.50/1 - 0.4 = \$14.17 Cheers, Penny Go to Math Central