I meant is - 99 rational or irrational?

-99 is rational because we can write it as - 99/1

A rational number is any number that can be written as a fraction, or ratio, of two whole numbers. The denominator cannot be zero.

Any integer or whole number is rational due to the fact we can just stick it over 1 to form a fraction. The reverse is not true. For example, the fraction 2/3 is rational but it's not a whole number.