Let the relations R1 and R2 on the set
X = {1, 2, 3, ..., 20} be given by
R1 = {(x, y) : 2x – 3y = 2} and R2 = {(x, y) : –5x + 4y = 0}. If M and N be the minimum number of elements required to be added in R1 and R2, respectively, in order to make the relations symmetric, then M + N equals
1
8
2
16
3
12
4
10