How do you balance Al+NO3(aq)---> Al(NO3)3(aq)+Ag(s)?

Answer 1

The Ag in the product can not appear out of no where. I assume the equation should have been written:

Al + AgNO3 > Al(NO3)3 + Ag

So . . . Al + 3AgNO3 > Al(NO3)3 + 3Ag

Get an "A".

Answer 2

I believe the equation you originally typed was faulty, and that there was a typing error. I hope so, because if not, the teacher you got this from is missing a few bolts. If the equation actually reads:
Al(aq) + NO3(aq) ---> Al(NO3)3 (aq) + Al (s)

then the balanced version of that is:

2Al(aq) + 3NO3(aq) ---> Al(NO3)3 (aq) + Al (s)