\[\boxed{\text{5.325.}}\]
\[\textbf{а)}\ 776 \cdot 16 + 324 \cdot 16 =\]
\[= 16 \cdot (776 + 324) =\]
\[= 16 \cdot 1\ 100 = 17\ 600\]
\[\textbf{б)}\ 384 \cdot 15 - 124 \cdot 15 =\]
\[= 15 \cdot (384 - 124) = 15 \cdot 260 =\]
\[= 3\ 900\]
\[\textbf{в)}\ 28\ 350\ :225 \cdot 45 - 1\ 673 =\]
\[= 3997\]
\[\textbf{г)}\ (4\ 976 + 1\ 524) \cdot 4 - 3\ 568 =\]
\[= 22\ 432\]