How do i write this in algebraic notation. i think of a number, i multiply it by two, and subtract 9

You are cycling around europe with friends. you book into a hostel and you ask the owner what the ratio of men to women is currently staying there. there are 24 men and 6 women. what is the ratio of men to women in its simplest form?

Can someone check if i did this correct. it’s number 4 if you’re wondering.

Can someone me out here and the tell me the greatest common factor