The extra residue was purposely left out and one has to be repeated by systematically solving it and finding where the last on goes. I'm just as confused as you on how to do this without the last or repeated residue. Any help would be appreciated.

2. An octapeptide was found to contain the following residues: G, K, M, P, R, W, E o Edman degradation yielded: -NH o Upon treatment with carboxypeptidases A, B, and Y, only carboxypeptidase Y had any effect o Trypsin treatment gave two tripeptides and a dipeptide Chymotrypsin treatment gave two tripeptides and a dipeptide Cyanogen bromide treatment yielded two tetrapeptides Clostripain treatment gave a pentapeptide and a tripeptide. Acid hydrolysis showed the tripeptide contained Gly.