\(n_{NO_2}=a\left(mol\right),n_{NO}=b\left(mol\right)\)
\(n_{hh}=a+b=0.4\left(mol\right)\)
\(m_{hh}=46a+30b=0.4\cdot22.5\cdot2=18\left(g\right)\)
\(\Rightarrow a=0.375,b=0.025\)
\(m_{Muối}=m_{kl}+62\cdot\left(n_{NO_2}+3n_{NO}\right)=9.93+62\cdot\left(0.375+3\cdot0.025\right)=37.83\left(g\right)\)