You have to understand how rational numbers are defined.
A rational number is any number that can be written as a quotient (a fraction) with an integer numerator and a non-zero integer denominator. In other words, if I delcare that n is a rational number then I can write n as:
n = q/p
where q and p are integers and p does not equal 0.
Alternatively, a rational number is any number that has a terminating or repeating decimal. An example of a terminating decimal is 1.325 because the decimal stops at 5. An example of a repeating decimal is 6.66666... (where the 6's go on forever). Numbers like 103 and 3546987929.1 are also examples of terminating decimals. IF the number is NOT a terminating or repeating decimal number, THEN the number is NOT a rational number.
Example: The number n = 1.2 is a rational number because it's a terminating decimal. Also 1.2 = 12/10, which is a fraction that contains only integers in the numerator and denominator.
Example: The number n = 3 is a rational number because it is a terminating decimal. Also 3 = 3/1 which is a fraction with integers on the numerator and denominator.
Example: The number n = 3.333333333.... (the 3's go on forever) is a rational number because it is a repeating decimal. Also it CAN be written as a fraction: 3.33333... = 10/3
, with an integer numerator and denominator.
Example: The number n = sqrt(2) is NOT a rational number. (NOTE: the "sqrt" means "square root" which is a function that asks the question: what number times itself equals this number. The sqrt(4) is 2 because 2 times itself equals 4). The sqrt(2) cannot be written as a fraction and it is a number that has a decimal which never repeats or terminates.
Notice that in your problem, the number is already written as a fraction: - 75/22. By the definition, this MUST be a rational number because its a fraction with integers in the numberator and denominator.