Respuesta :

Answer:

z = -5

Step-by-step explanation:

3(0.7z + 2.8) = 7(1.5z + 7.2)

2.1z + 8.4 = 10.5z + 50.4

2.1z - 10.5z = 50.4 - 8.4

-8.4z = 42

z = 42/(-8.4)

z = -5