\[\boxed{\text{5.555.}}\]
\[\textbf{а)}\ 270 - 214 = 56\ :28 =\]
\[= 2 \cdot 37 = 74 + 26 = 100\ \]
\[\textbf{б)}\ 100\ :25 = 4 \cdot 15 = 60\ :12 =\]
\[= 5 \cdot 180 = 900\]
\[\textbf{в)}\ 60 - 12 = 48\ :8 = 6 \cdot 10 =\]
\[= 60\ :5 = 12\]
\[\textbf{г)}\ 140 - 63 = 77\ :7 = 11 + 4 =\]
\[= 15 \cdot 4 = 60\]