Answer:
Comparing the cost of replacing the modem with a router/modem and its need in day today changing life.
Step-by-step explanation:
As you known modem devices develop at a very gradual pace, you can normally use a modem for months, until it breakdown, but you might need to substitute a router because you require a more reachable area. After all, you've joined more computers to your web and your old router isn't holding up, or because you need to take the support of the latest development.