According to the given equation, the number of NO3 ions in the reactants is 1 and in the products is 2, so to balance the equation we have assign 2 as the coefficient of AgNO3.
Also, assign 2 as the coefficient of Ag.
[tex]2AgNO_3+Cu\to Cu(NO_3)_2+2Ag[/tex]
The first box must be filled in with a 2, the second and third boxes must be left empty and the last box must be filled in with a 2.
