How can I solve a logistics regression if it includes an unknow in the parameter Let's say the logistics regression is
log(p)= -300+ 0.5xAge + 80xGender
given Age=3; Gender = unknown
how can I solve this logistics regression?
The answer is -300?-298.5(simply sum the first two parameters)? 0?or it can't be calculated?
Does it mean that we should include all the parameter to calculate the equation?

Imagine this was a general equation such as
$$y=1.6x+0.7z$$
and the question is how can you "solve" this if you do not know $z$? You can't. You will either have to make something up for $z$, or in your case - since $z$ is a dummy binary variable (I assume) - try both cases and report both results or maybe some average of them.
Example if you have two genders coded as 0 for males and 1 for females then the log odds equation for males is $\log(\frac{p}{1-p})=-300+0.5 \cdot Age+80 \cdot 0$ and for females it's $\log(\frac{p}{1-p})=-300+0.5 \cdot Age+80 \cdot 1$, so a difference of $80$ in log odds. You can report both these values or maybe some average of them on the original scale.
