\(\left(\frac{7}{19.31}+\frac{5}{19.43}+\frac{3}{23.43}+\frac{11}{23.57}\right):\left(\frac{1}{31}-\frac{1}{57}\right)\)
\(=\frac{7}{19}.\frac{7}{31}+\frac{5}{19}.\frac{5}{43}+\frac{3}{23}.\frac{3}{43}+\frac{11}{23}.\frac{11}{57}:\frac{1}{31}-\frac{1}{57}\)
\(=\frac{7}{19}+\frac{5}{19}.\frac{7}{31}+\frac{1}{31}:\frac{5}{43}-\frac{3}{43}.\frac{3}{23}+\frac{11}{23}.\frac{11}{57}+\frac{1}{57}\)
\(=\frac{12}{19}.\frac{8}{31}:\frac{2}{43}.\frac{7}{16}.\frac{4}{19}\)
\(=\frac{1204}{1767}\)