What is the opportunity cost (in civilian output) of a defense buildup that raises military spending from 4.1 to 4.5 percent of a $7 trillion economy?

Assuming the build-up in military defense completely crowds out civilian output (as resources are diverted from the private sector), then the 0.4% increase in military spending will lead to an equal 0.4% decrease in civilian output (as a proportion of the $7 trillion economies). 
You need to multiply $7 Trillion by 0.004 (0.4%) 
$7,000,000,000,000 X 0.004 = $28,000,000,000 
and the opportunity cost (in civilian output) of a defense buildup is $28 Billion.
Opportunity cost is the benefit that the person can be received, but they gave up, to take another course of action. It is also a benefit, profit or value of something they give up to achieve or acquire something else.

Prior to the creation of the us constitution, the general view of representative government is that it only worked in very small-scale environments- essentially a city-state or smaller. otherwise, the actual reflection of popular will declined in the representatives (ie, the difference between 1 representative per 100 citizens and 1 representative per 10,000 citizens), and generally the whole process became inefficient and self-destructive.james madison, however, was like 'no beezy'. he remarked that small republics were prone to faction and thus collapsed quickly. a large republic, he said, had so many interests and factions that none could rule, and thus they had to moderate and compromise.

Of course it’s correct because you know why if you readi you did not put. any numbers but i understand so your promblem is yes and correct