Which statement best describes how physical features contributed to Mesopotamian settlements? A. Mountain ranges protected them from nearby enemies.
B. Changing temperatures provided for widely varied crops.
C. The seas were a natural barrier that protected growing of crops.
D. The favorable climate and rich soil provided for their physical needs.

2018 means 2018 ce or common era

there have been other eras too including bce, which included way more years.

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

the correct answer is batering