Which factors led to the development of the four river valley civilizations of mesopotamia, egypt, the indus valley and china? choose all that applya. the ability to communicate widely through writingb. a nearby riverc. people doing different jobsd. the building of villages and citiese. the construction of places of worship

D. The building of villages and cities.

B. A nearby river

C. People doing different jobs.

Explanation:

I took the test.

Hope this helps !

hilary clinton

explanation:

trump won the popular vote and ended up becoming the president in 2016 because of this and the electoral college.

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