What does the phrase “last in, first out” mean?

On january 1, 2017, sophie's sunlounge owned 4 tanning beds valued at $20,000. during 2017, sophie's bought 3 new beds at a total cost of $14 comma 000, and at the end of the year the market value of all of sophie's beds was $24 comma 000. what was sophie's net investment

In the united states, one worker can produce 10 tons of steel per day or 20 tons of chemicals per day. in the united kingdom, one worker can produce 5 tons of steel per day or 15 tons of chemicals per day. the united kingdom has a comparative advantage in the production of:

Google started as one of many internet search engines, amazon started as an online book seller, and ebay began as a site where people could sell used personal items in auctions. these firms have grown to be so large and dominant that they are facing antitrust scrutiny from competition regulators in the us and elsewhere. did these online giants grow by fairly beating competition, or did they use unfair advantages? are there any clouds on the horizon for these firms -- could they face diseconomies of scale or diseconomies of scope as they continue to grow? if so, what factors may limit their continued growth?