Which of following did not contribute to the civil war? a. federal versus states’ rights b. the emancipation proclamation c. slavery and territorial expansion d. the outcome of the 1860 election

i just need the points

explanation:

four sitting presidents have been assassinated while in office but the first was abraham lincoln,

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

tea which is where the whole thing about dumping it in the ocean came from