\[\boxed{\text{4.\ 219}}\]
\[187,86\ :6\frac{1}{5} = 187,86\ :6,2 =\]
\[= 18\ 786\ :620 = 30,3\]
\[30,3 - 19,4 = 10,9\]
\[70,85 + 9,35 = 80,2\]
\[80,2 \cdot 22\frac{1}{2} = 80,2 \cdot 22,5 =\]
\[= 1804,5\]
\[298,08\ :7,2 = 29\ 808\ :720 =\]
\[= 41,4\]
\[41,4 - 32,9 = 8,5\]
\[54,4 + 26,1 = 80,5\]
\[80,5 \cdot 32\frac{3}{5} = 80,5 \cdot 32,6 =\]
\[= 2624,3\]