E1. Marin Golf Stores, Inc. operates a chain of golf equipment stores in the Western United States. In 2017 the company ran a promotion, providing customers with coupon each time a customer bought a dozen of a specific brand of golf balls. After accumulating five coupons, a customer could present the coupons to the store in exchange for a free golf hat. In 2017, Marin purchased 1,500 of the hats for the promotion at $8 each and sold 11,100 dozen golf balls eligible for the promotion at $50 per dozen. Customers presented 2,800 of the coupons for redemption in 2017. Customers have until June 30, 2018 to present coupons in exchange for a free hat. Estimates indicate that a total of 80% of the coupons will eventually be presented for redemption. Prepare all the entries that would be made relative to sales of the golf balls included in the promotion and to the golf hat premium plan in 2017.

Premium Expense 4,480

Inventory of Premiums 4,480

Premium Expense 9,728

Premium Liability 9,728

Please explain why bolded expense is correct. I was able to compute first entry, but not second. Thank you!