Islam expanded rapidly in part because select one: a. the greek orthodox church's belief in arianism had alienated many christians. b. western latin christians opposed the byzantine empire. c. conquests by abbasids had softened up the byzantines. d. the reorganization of the themes and strategoi in arabia made the muslim army more efficient. e. their toleration for "people of the book."

The right answer is e.

Explanation:

At least during the first century of Islam, under the rule of the Umayyad dynasty, Islamic rulers were more tolerant of Jews and Christians who even occupied some high public posts in some societies.  Later, stricter rules were enforced , including forced conversion.  

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