im fairly new to math and im trying to find all elements of equivalance class [-1] and [4/5] for the following equivalance relation
For a, b, c, d ∈ Z with b, d ≠ 0: a/b R c/d ⇔ ad = bc.
Ive deduced its an equivalent statement, being reflexive, symmetric and transitive but im unsure how to express the equivalent classes of [-1] and [4/5]?