A circuit node has current ia entering and currents ib and ic exiting, where it is known that ia=5 ma and ib=9 ma. what is current ic?

The current is the flow of electrons. It is expressed as Coulombs per second, or Amperes. Since it is a flow, all that comes in must go out. The basis here is the node. Since ia is the full flow, it must be greater than ib or ic. So, I think the given information is wrong. It should be ia = 9 mA and ib=5 mA.

Current entering = Current leaving

ia = ib + ic

9 mA = 5 mA + ic

ic = 9 mA - 5 mA = 4 mA