Let the relations \( R_1 \) and \( R_2 \) on the set \( X = \{1,2,3,\ldots,20\} \) be given by \( R_1 = \{(x,y): 2x - 3y = 2\} \) and \( R_2 = \{(x,y): -5x + 4y = 0\} \). 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.
