if you are short on time, these resources are you best bet for this topic:
Combined arms is an approach to warfare which seeks to integrate different combat arms of a military to achieve mutually complementary effects (for example, using infantry and armor in an urban environment, where one supports the other, or both support each other) ADRP 3-0: Unified Land Operations
According to strategist William S. Lind, combined arms can be distinguished from the concept of "supporting arms" as follows: Combined arms hits the enemy with two or more arms simultaneously in such a manner that the actions he must take to defend himself from one make him more vulnerable to another. In contrast, supporting arms is hitting the enemy with two or more arms in sequence, or if simultaneously, then in such combination that the actions the enemy must take to defend himself from one also defends himself from the other(s).