Question

8(
–
9+2n)–9n=
–
9
n=

Answer 1

First simplify:

8(−9 + 2n) − 9n
= 8·(−9) + 8·2n − 9n
= −72 + 16n − 9n
= −72 + 7n

So the expression simplifies to 7n − 72.

If you meant the equation 8(−9 + 2n) − 9n = −9n, then
7n − 72 = −9n
16n − 72 = 0
16n = 72
n = 72/16 = 9/2 = 4.5.