A very old huge computer classroom consists of 120 nodes. Currently, there are 5 hubs (each has 24 ports) connecting through an 8-ports hub before reaching to the modem for Internet access. The most often encountered problem in this classroom is computer networking problem. The network speed is terrible and may not work all the time. Some expert checked the network and left a message saying that too many collisions happen in the network. As a network manager, how would you solve this problem with "somewhat limited budget" and no-reconfiguration of the network layout? (Provide justification to your solution!)