Sets And Relations

Let the relations \(R_1\) and \(R_2\) on the set \(X=\{1,2,3, \ldots, 20\}\) be given by \(R_1=\{(x, y): 2 x-3 y=2\}\) and \(R_2=\{(x, y):-5 x+4 y=0\}\). If \(M\) and \(N\) be the minimum number of elements required to be added in \(R_1\) and \(R_2\), respectively, in order to make the relations symmetric, then \(M+N\) equals