Respuesta :

Answer : D

Cross multiply:
9n + 63 = 8n + 40

Subtract 63 from both sides:
9n + 63-63= 8n + 40-63

Simplify:
9n=8n-23

Subtract 8n from both sides:
9n-8n= 8n-23-8n

Simplify:
n=-23