First find \(SNR_{c}\), for to find \(SNR_{i}\) use the following
\(SNR_{i}=SNR_{c}\frac {B}{B_{T}}\), where \(B_{T}\) is the transmission bandwidth, and \(B\) is the baseband bandwidth. For \(AM\), \(B_{T}=2B\). For \(DSB-SC\), \(B_{T}=2B\). For \(DSB-SS\), \(B_{T}=B.\)