Understanding Equivalence Relations

Understanding Equivalence Relations

For $$A = \{(−4, −20), (−3, −9), (−2,
−4), (−1, −11), (−1, −3), (1, 2), (1, 5),
(2, 10), (2, 14), (3, 6), (4, 8), (4, 12)\}$$ define the relation $R$ on
$A$ by $(a, b) R (c, d)$ if $ad = bc$.
a) Verify that $R$ is an equivalence relation on $A$.
b) Find the equivalence classes $[(2, 14)], [(−3, −9)],$ and
$[(4, 8)]$.
c) How many cells are there in the partition of $A$ induced by $R$?