We first find the slopes of the two lines: 2/M and -1/4 For two lines to be perpendicylar, the product of their slopes must be equal to -1. Hence the equation (2/M)*(-1/4) = -1. Solve for M to find M = 1/2. Solution We first find the slopes of the two lines: 2/M and -1/4 For two lines to be perpendicylar, the product of their slopes must be equal to -1. Hence the equation (2/M)*(-1/4) = -1. Solve for M to find M = 1/2..