50:z=

The expression "50:z=" appears to suggest a proportion or a mathematical equation involving the value "50" and a variable "z." However, without additional context, it's difficult to provide a specific answer.

If you meant to solve for "z" in the context of a proportion, it might look something like this:

1. If it’s a simple equation, you might be looking for an equation like \( 50 = kz \) for some constant \( k \). In this case, you would solve for \( z \) as \( z = \frac{50}{k} \).

2. If it’s part of a ratio, you might write it as \( \frac{50}{z} = k \) for some constant \( k \), leading to \( z = \frac{50}{k} \).

If this isn’t what you were looking for, please provide additional details or clarify the context, and I would be happy to assist further!