Let A be the same set as in given Exercise. Show that the following relation is an equivalence relation:

(m1,n1)p(m2,n2) if m1+n2 = n1+m2. Draw the equivalemce class of (1,2).

Exercise
Let A = J+ X J+, where J+ is the set of positive integers. Define a relation in A as follows: If (m1,n1) and (m2,n2) are elements in A, then (m1,n1) if m1,n2 = n1,m2. Show that is an equivalence relation and describe its equivalence classes.