Just take it one step at a time.
We must first show tha a~a.
so is (a, b) ~ (a, b)?
That is, ab = ba? If you are doing multiplication (which I assume), then yes, that statement is true.
Now let's assume a ~ b. Show that b ~ a.
Since a ~ b, ad = bc. So cb = da, and thus, b ~ a.
Now you try transitivity. Assume that a ~ b and b ~ c. Try to show that a ~ c.