A decapeptide (Mol. Wt. 796) on complete hydrolysis gives glycine ( Mol.wt.75), alanine and phenylalanine. Glycine contributes 47.0% to the total weight of the hydrolysed products. The number of glycine units present in the decapeptide is 

Molecular weight of decapeptide = 796 g/mol
Total bonds to be hydrolysed = (10 – 1) = 9 per molecule
Total weight of $H_{2}O$ added $=9\times 18=162g/mol$
Total weight of hydrolysis products $=796+162=958g$ 
Total weight % of glycine (given) = 47%
Total weight of glycine in product $=\frac{958\times 47}{100}g=450g$
Molecular weight of glycine $=75g/mol$
Number of glycine molecules $=\frac{450}{75}=6$ .
Note: A dipeptide has one peptide bond. Thus, a decapeptide has 9 peptde bonds.