I am trying out operations on sets and i have become stuck on how you could update set of pairs, say I have a set $A$: $A = \{(a,3),(b,5),(c,7)\}.$
If I wanted to add a pair I would use the union of the two sets; $A \cup \{(x,8)\}.$ Or remove one I would use the set difference; $A \setminus \{(b,5)\}$ How do you go about updating $a$, $b$ in the pair $(a,b)$ in set $A$?