The answer depends on whether you mean additive opposite or multiplicative opposite. Assuming the former, the sum of the two numbers is zero.
They do not. There is no relationship between rational numbers and rational decisions.
The set of integers is a proper subset of the set of rational numbers.
Rational numbers form a proper subset of real numbers. So all rational numbers are real numbers but all real numbers are not rational.
They are all numbers
A rational number is one which can be expressed as a ratio of two integers.
Counting numbers are a proper subset of whole numbers which are the same as integers which are a proper subset of rational numbers.
They are both representations of rational numbers.
Find the arithmetic average of the two rational numbers. It will be a rational number and will be between the two numbers.
-- Every whole number is a rational number. -- Any whole number divided by any whole number (except zero) produces a rational number.
There are an infinite number of rational numbers between any two rational numbers.
There are infinitely many rational numbers between any two rational numbers. And the cardinality of irrational numbers between any two rational numbers is even greater.
There are more irrational numbers between any two rational numbers than there are rational numbers in total.