Answer: R ∩ S = {20}.
Step-by-step explanation: We are given the following two sets :
R = {10, 15, 20}
and
S = {20, 25}.
We are to find the intersection of the sets R and S, .i.e., R ∩ S.
We know that
the intersection of two sets is a set that contains the elements which are common to both the sets.
Therefore, the intersection of the sets R and S is given by

Thus, R ∩ S = {20}.