Why do you think World War I is referred to as the “first modern war"

Because the following month, Germany sunk four more U.S. merchant ships. On April 6, 1917, the United States entered World War I. Get a firsthand look at how a new breed of weapons like WMDs, submarines, armored tanks and air attacks changed modern warfare forever in WWI: The First Modern War.

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swe hold these truths to be self-evident, that all men are created equal, that they are endowed by their creator with certain unalienable rights, that among these are life, liberty and the pursuit of happiness. — that to secure these rights, governments are instituted among men, deriving their just powers from the consent of the governed, — that whenever any form of government becomes destructive of these ends, it is the right of the people to alter or to abolish it, and to institute new government, laying its foundation on such principles and organizing its powers in such form, as to them shall seem most likely to effect their safety and happiness. "

- declaration of independence

  according to this passage from the declaration of independence, who gives government the power to exist?

a) the king

b) the people

c) their creator

d) their governmenthook

the perimeter of a triangle is 69 cm. side a is 5 cm shorter than side b. side c is twice as long as side a. find the length of each side. i need to know how to do it in 2 equations.  

equations:

a = b-5

c = 2a

a + b + c = 69