What role did timbukutu play in mali's empire

monitor contract compliance and results of forestry activities to assure adherence to government regulations.  

plan and supervise forestry projects, such as determining the type, number and placement of trees to be planted, managing tree nurseries, thinning forest and monitoring growth of new seedlings.  

establish short- and long-term plans for management of forest lands and forest resources.  

determine methods of cutting and removing timber with minimum waste and environmental damage.  

supervise activities of other forestry workers.

by the way there is no video here.

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