Let's use an example: Sale Price (P)=$40, Discount (D)=$0, Shipping Charged (S_buyer)=$5, COGS=$10, Shipping Cost (S_seller)=$3, Listing Fee (L)=$0.20, Transaction Fee (T_pct)=6.5%, Payment Processing (PP_pct)=3% + Fixed (PP_fixed)=$0.25, Offsite Ads (OA_pct)=12%.