All along the axis of a uniformly charged disk, at a point 0.6 m from the center of the disk, the potential is 55.5 V and the magnitude of electric field is 62.2 V/m; at a distance of 1.5 m, the potential is 26.4 V and the magnitude of the electric field is 16.1 V/m. Determine the net charge residing on the disk.