What makes Fort Sill historically unique among other regional military installations? A. It is the site where seven major commanders of US military efforts were trained,
B. It houses the largest explosive weapons factory in the United States,
C. It specializes in training soldiers to preserve the cultural artifacts of nations invaded by the US
military
D. It is the oldest functioning installation in Oklahoma,

D. It is the oldest functioning installation in Oklahoma,

Explanation:

it's the only still-functioning fort established in the southern Great Plains in the 1800s. It's got a pretty long legacy.

cultural achievements of the 1920's 2010  

1. cultural achievements and african american achievements in the 1920’s  

2. art and literature charles lindberg flew from ny to paris, france. became national hero; first transatlantic flight.  

3. greenwich village (new york) and the south side (chicago)  many artists, writers, and intellectuals flocked to these areas to share ideas  people lead bohemian, or artistic and unconventional, lifestyles

simplify brackets

8 - 2a - 7 = a + 40

simplify 8 - 2a - 7 to -2a + 1

-2a + 1 = a + 40

add 2a to both sides

1 = a + 40 + 2a

simplify a + 40 + 2a to 3a + 40

1 = 3a + 40

subtract 40 from both sides

1 - 40 = 3a

simplify 1 - 40 o -39

-39 = 3a

divide both sides by 3

-39/3 = a

simplify 39/3 to 13

-13 = a

switch sides

a = -13