How did the kingdom of ghana become wealthy from the african gold-salt trade?

a. it had several gold mines within its kingdom and became rich trading the gold.

b. it the rulers of the umayyad empire conquer north africa in exchange for gold.
c. it imposed a tax on the production of salt, which was nearly as valuable as gold.

d. it imposed taxes on merchants who used gold trade routes that passed through ghana

D. It imposed taxes on merchants who used gold trade routes that passed through Ghana

D. It imposed taxes on merchants who used gold trade routes that passed through Ghana.

Explanation:

The Kingdom of Ghana or Ghana Empire was a West African empire that was located in what is now Mauritania and Mali. The empire gained prominence around the 7th century due to its profiting from the African gold-salt trade. One of the ways in which the kingdom became wealthy was by imposing taxes on merchants who used the routes that passed through Ghana.

what the first or next guy says

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