Solve the following system of equations.

n= -6, a= 5

Step-by-step explanation:

Label the two equations:

a= -2n -7 (1)

-3a +n= -21 (2)

Substitute (1) into (2):

-3(-2n -7) +n= -21

Expand:

-3(-2n) -3(-7) +n= -21

6n +21 +n= -21

Simplify, minus 21 on both sides:

7n= -21 -21

7n= -42

Divide both sides by 7:

n= -42 ÷7

n= -6

Substitute n= -6 into (1):

a= -2(-6) -7

a= 12 -7

a= 5

step-by-step explanation:

descending order means to order the polynomials from the term with the largest exponent to the term with the smallest exponent.  

therefore, the correct answer is d.