12+z:8=21

To solve the equation \( \frac{12 + z}{8} = 21 \), you can follow these steps:

1. Multiply both sides of the equation by 8 to eliminate the fraction:

   \[ 12 + z = 21 \times 8 \]

   \[ 12 + z = 168 \]

2. Next, subtract 12 from both sides to isolate \( z \):

   \[ z = 168 - 12 \]

   \[ z = 156 \]

So, the solution is \( z = 156 \).