World War I lasted four years. What were the war years?

WWI started in 1914 and lasted till  1918

Explanation:

World War I (WWI or WW1), also called the First World War, began on July 28, 1914 and lasted till November 11, 1918. The war was a global war that lasted exactly 4 years, 3 months and 14 days.

the california missions began in the late 18th century as an effort to convert native americans to catholicism and expand european territory. there were 21 missions in all, lasting from 1769 until about 1833.   the missions were built by the spanish starting in 1769 in order to “colonize” the territory of alta california. so the missions were important because they were the means of settling california. it also wanted to keep other european countries out of alta california. building settlements along the coast would them meet these goals. missionaries wanted to convert the indians to the roman catholic faith. california indians did much of the work to build missions.

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