You are asked to partition the Departmental network address block to create separate staff and student sub-networks. Your network must be able to support up to 120 machines on the staff network (not counting the router) and up to 640 machines on the student network (also not counting the router). You must choose the largest possible network address for the student network. You must then choose the smallest possible network address for the staff network. You must also choose the smallest possible size for the two sub-networks so that a visitor/guest network can be established in the future with the remaining network capacity.

What is the network address of of the student network?