A pair of spiral gears is required to connect two shafts, the angle between the non-intersecting axes is \(90^{\circ}\). The speed ratio is 3 and pitch circle diameters of the gears are equal. If approximate centre distance is \(250 \mathrm{~mm}\), estimate the helix angle of gears and number of teeth on each gear. Take module \(=3 \mathrm{~mm}\).