An integer is a whole rational number. (Rational numbers can be represented with a fraction.)
The opposite of any integer is its negative. Let's use 100 as an example. Since 100 is a whole number, its opposite would be -100. The same goes with all other integers.
An integer is a whole number. Two integers are opposite if they have the same distance away from zero. For example, 2 and -2 or 28 and -28 Those are all integers and opposites.