A certain fractional distillation apparatus contains a 24-cm Vigreux column stacked on top of a 30-cm glass tube that is half-filled with 4x4-mm porcelain saddles. This assembly is inserted into a boiling flask. How many theoretical plates does the column assembly provide is the HETP of the saddles is 5 cm, the HETP of the Vigreux column is 8 cm, and the HETP of the empty glass tube is 15 cm?