about how long a ago did humans arrive in the Americas? A.15,000 years ago. B.100,000 years ago. C.1,500 years ago. D.50,000 years ago​

The answer would be around 13,000 years ago but as it's not a option, (A) would be your answer

Explanation:

The Clovis first theory refers to the 1950s hypothesis that the Clovis culture represents the earliest human presence in the Americas, beginning about 13,000 years ago.

c holding free elections

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