Weeks of Supply, Sell through % and Build Practice Problems vendor to retail at $89.00. In the 74. A buyer purchases 1,200 sandals from a vendor to reta first week, the buyer sold 30 pairs at regular price. a Calculate the WOS and ST % for week 1. b The second week, the buyer sold 40 pairs at regular price. Calculat the WOS and ST % for week 2. What was the build in unit sales for week 2 from week 12 c. The third week, the buyer took a POS markdown to $69.99 and sold 65 pairs. Calculate the WOS and ST % for week 3. d. What is the markdown % to the customer and what is the mark- down % to the retailer (journal)? e. Calculate the build in unit sales from week 3 to week 2