Although a number of things brought about world war 1 there was one event that pushed europe power the edge, what was that event ?

There are multiple things that caused the beginning of World War I. However, there was a certain event that pushed the power of Europe on its edge and that was when Archduke Ferdinand was assassinated. This is the reason why Europe was being caught in the World War I.

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

an interest group is an organization whose members share common concerns, and try to influence government policies that impact those concerns. elected officials frequently complain about the influence of "special interests" on american politics.