How to restructure nested if else statement

Say you have the following table for a monster object:

Gender	Age	Type	Result
Male	Young	Fire	1
Male	Old	Ice	2
Male	Old	Wood	6
Female	Young	Fire	4
Female	Old	Ice	5
Female	Old	Wood	8
Other	Young	Fire	7
Other	Old	Ice	10
Other	Old	Wood	20

If I were to have a monster and input it to get a result; how would I get the result of the monster object without making a long nested if-else statement?

if(monster.Gender == Male && monster.Age == Old)
    if(monster.Type == Ice)
        return 2
    if(monster.Type == Wood)
        return 6
if(monster.Gender == Male && monster.Age == Young)
etc...

I can't seem to wrap my head around making it extensable and such: say I want to add a column in the future or want to validate something before another thing.

Are there any simple design patterns or the like that I can implement to simplify it and make it extensible?