Final answer:
All fractions equivalent to -2/3 are found in the set of rational numbers because -2/3 is expressible as the quotient of two integers, making it a rational number.
Step-by-step explanation:
The question asks in which set are all fractions equivalent to -2/3. A fraction is equivalent to another if you can multiply or divide the numerator (top number) and the denominator (bottom number) by the same non-zero number to get the other fraction. The fraction -2/3 is a rational number because it can be expressed as the quotient of two integers (2 and 3) where the denominator is not zero. Integers and whole numbers cannot be equivalent to -2/3 because they do not include fractions or negative numbers, while irrational numbers are not expressible as simple fractions or ratios of integers.