When 13.0 g of silver is produced, _____ g of zinc nitrate is also produced.

Zn(s) + 2AgNO3(aq) 2Ag(s) + Zn(NO3 )2(aq)

mols Ag = grams/molar mass

Convert mols Ag to mols Zn(NO3)2 usig the coefficients in the balanced equation.
Now convert mols Zn(NO3)2 to g. g = mols x molar mass.