During the ___ Era, humans left the continent of ___ and spread across the globe. They were , which means they moved from place to place in search for food. They survived by tracking game and collecting plants and berries, a practice called

1. PALEOLITHIC

2. AFRICA

3. NOMADS

4. UNTING AND GATHERING.

Explanation:

a historian researching the immigration policies of the early 1900s would expect a source written today,rather than in 1910 to :

( a ) be more interested in objective data and statistics.

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