30:(17 16/19-15 16/19)+(7 3/5-4 4/5).
\[30\ :\left( 17\frac{16}{19} - 15\frac{16}{19} \right) + \left( 7\frac{3}{5} - 4\frac{4}{5} \right) =\]
\[= 30\ :2 + \left( 6\frac{8}{5} - 4\frac{4}{5} \right) = 15 + 2\frac{4}{5} =\]
\[= 15 + 2,8 = 17,8.\]