Answer:
 Ag is the oxidizing agent
Step-by-step explanation:
oxidizing agent in the following equation? 
Al (s) + 3 Ag+ (aq) = Al+3 (aq) + 3 Ag (s)
Left side
Al = 1
Ag = 3
Right Side
Al = 1
Ag = 3
So it's balanced already good.
Define
oxidizing agent = An oxidizing agent is the substance that gains electrons and is reduced in a chemical reaction.
Al is the reducing agent. 
 Ag is the oxidizing agent