Communication between a computer and a keyboard involves?

Afreelance​ singer-songwriter is planning the restoration of a recently purchased civil​ war-era farmhouse. while he professes an enjoyment​ of, and talent in the construction​ trades, the theory of comparative advantage implies that a. the value of what he imports​ (in this​ case, professional contractor​ services) must equal the value of what he exports​ (songs). b. he should concentrate on the restoration work since his​ out-of-pocket costs will be much lower than if he hires professionals. c. ​self-sufficiency is​ advantageous, hence he should split his time between music and construction. d. the income lost while away from music will likely exceed the savings realized by doing the work​ himself, thus, he should hire professionals to do the restoration work. e. he ought to do as much of the work himself as possible since imports​ (in this​ case, professional contractor​ services) should always be restricted to those things that cannot be done internall

Which statement is true of both presidential and parliamentary systems of government? a. the executive branch operates independently from the legislative branch. b. the members of the legislative branch are directly elected by the people. c. the head of government is chosen by members of his or her political party. d. the head of government is directly elected by the people

When a company produces and sells x thousand units per week, its total weekly profit is p thousand dollars, where upper p equals startfraction 800 x over 100 plus x squared endfraction . the production level at t weeks from the present is x equals 4 plus 2 t. find the marginal profit, startfraction dp over dx endfraction and the time rate of change of profit, startfraction dp over dt endfraction . how fast (with respect of time) are profits changing when tequals8?