Respuesta :

Answer:

x = 6, BC = 60

Step-by-step explanation:

6x + 2x + 1 = 81

8x + 1 = 81

8x (+ 1 - 1) = 81 - 1

8x = 80

8x/8 = 80/8

x = 10

6x

6(10) = 60