The 1954 Statelessness Status Convention provided a definition of a stateless person (which has since become part of customary international law, according to the International Law Commission), and sets out a number of rights that stateless persons should enjoy.
The ratio of two integers P and Q can be expressed as P : Q or P/Q. In both cases, you may divided P and Q by their greatest common factor so as to express the ratio in its simplest form.
Just think of addition and subtraction as directions on the number line. There are also several rules and properties that define how to perform these basic operations. To add integers having the same sign, keep the same sign and add the absolute value of each number. To add integers with different signs, keep the sign of the number with the largest absolute value and subtract the smallest absolute value from the largest. Subtract an integer by adding its opposite. Watch out! The negative of a negative is the opposite positive number.