Question

For the reactions that occurred spontaneously in the individual tables, balance these reactions assuming they are in an acidic solution.

Reaction 1:
Cu
I^-
Ag
Br^-

Reaction 2:
Zn
Pb
Cu
Ag

Reaction 3:
Cl2
Br2
I2

Reaction 1
I 2(aq) Cu2 + (aq) Ag + (aq) Br2 (aq)

Reaction 2
Ag + (aq) Pb2 + (aq) Cu2 + (aq) Zn2 +(aq)

Reaction 3
Br - (aq) Cl - (aq) I - (aq)

Answer 1

Your notation is still somewhat confusing to me but here is what you do for one of the reactions. The others are done the same way.
For the copper, Ag^+ reaction:
Cu ==> Cu^+2 + 2e
Ag^+ + e ==> Ag
====================
The electrons must be kept equal; therefore, multiply the first equation by 1 and the second equation by 2, then add them.
Cu + 2Ag^+ ==> Cu^+2 + 2Ag.

The others are done the same way.