Formula for Calculating Tensile Stress?

Can you help me create a formula for calculating eBay profit after fees?

• Let's, for sake of discussion, assume I want to make $100.00 profit for selling an item on eBay. This $100.00 is AFTER all fees (including shipping) have been taken/paid. I would want a formula that if I were to input $100.00, the output would be the total amount I would have to sell the item for to account for all of the fees. This formula should factor in the shipping cost (flat rate), eBay final value fee(s), and PayPal transaction fee. In my above example of $100.00, I know that I would need to sell the item for $139.43 in order to have $100.00 profit. I figured that out with trial and error. But what is the formula if I wanted to figure it out for different amounts? Here are the knowns: ebay_final_value_fee1 = 5% of first $50.00 ebay_final_value_fee2 = 7% of remaining balance shipping_cost = $27.00 paypal_fee = 3.2% of total amount received from buyer

• Answer:

  In general; profit = sell price - fees profit = sell price - [shipping + paypal fee + ebay fee1 + ebay fee2] //IF you sell it for over $50 profit = sell price - [shipping + (.032 * buy price) + (.05 * 50) + (.07 * (sell price - 50))] //IF you sell it for less than $50 profit = sell price - [shipping + (.032 * buy price) + (.05 * sell price))] If you're only planning on selling items for more than $50, then look at the first equation. But let's figure out buy price first... I'm slightly confused here. I guess that would be the sell price (price you're selling it for) minus all of the fees from ebay and not including shipping, right? So buy price = sell price - 0.5(50) - (.07)(sell price - 50) buy price = sell price - 2.5 - .07sell price + 3.5 buy price = sell price(.93) + 1 Let P = profit S = sell price H = shipping B = buy price (amount received from buyer) profit = sell price - [shipping + (.032 * buy price) + (.05 * 50) + (.07 * (sell price - 50))] P = S - [H + (.032B) + 2.5 + (.07 * (S - 50))] P = S - [H + (.032B) + 2.5 + .07S - 3.5] P = S - [H + (.032)(.93S + 1) + .07S - 1] There I just expressed the paypal fee in terms of sell price. Now to combine terms. P = S - [H + .02976S + .032 + .07S - 1] P = S - [H + .09976S - .68] P = S - H - .09976S + .68 P = .90024S - H - .68 Wow. Well, not sure how accurate that is, but it seems about right. So let's try that out on your example. P = .90024S - H - .68 100 = .90024S - 27 - .68 100 + 27 + .68 = .90024S S = 127.68/.90024 S = $141.83 Well, it's pretty close. You can check my math if you want :) Hope that helps.