Hello i'm a little bit bored

Alocal barnes and noble bookstore ordered 80 marketing books but received 60 books. what percent of the order was missing?

An allergy products superstore buys 6000 of their most popular model of air filters each year. the price of the air filters is $18. the cost of ordering and receiving shipments is $12 per order. accounting estimates annual carrying costs are 20% of the price. the supplier lead time is 2 days. the store operates 240 days per year. each order is received from the supplier in a single delivery. there are no quantity discounts. what is the store’s minimum total annual cost of placing orders & carrying inventory?

How is challah bread made? if i have to dabble the recipe?