Answer:
[tex] \boxed{b = 140} [/tex]
Step-by-step explanation:
[tex] = > \frac{b}{7} - 12 = 8 \\ \\ = > \frac{b}{7} = 8 + 12 \\ \\ = > \frac{b}{7} = 20 \\ \\ = > b = 20 \times 7 \\ \\ = > b = 140[/tex]
