A and B in algebra stand for any variables of real numbers. A real number is a value of a continuous quantity that can represent a distance along a line. So if you see A and B in doing your algebra it is just a representation of a value that you need to find.
The answer is c). “o” means and or also
A) because it's man (Hans) and woman (Helga), so you can't choose female (alemanas) and two are plural
