If the foot of the perpendicular from the point \(A(–1, 4, 3)\) on the plane \(P : 2x + my + nz = 4\), is \(\left(-2, \frac{7}{2}, \frac{3}{2}\right)\), then the distance of the point A from the plane P, measured parallel to a line with direction ratios \(3, –1, –4\), is equal to