What abolitionist wanted to start a slave rebellion and raided Harper’s Ferry, Virginia?

Harpers Ferry Raid, (October 16–18, 1859), assault by an armed band of abolitionists led by John Brown on the federal armory located at Harpers Ferry, Virginia (now in West Virginia). It was the main precipitating incident to the American Civil War.

Explanation:

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