в) Вычислите: \(\dfrac{8:\left(3:\left(2\dfrac34-1\dfrac{15}{28}\right)+\dfrac23:\dfrac32\right)+\dfrac{57}{223}}{14\cdot\left(5\dfrac57-4\dfrac34\right)-9\dfrac57+\dfrac3{13}}\).

\[2\frac34-1\frac{15}{28}=\frac{11}{4}-\frac{43}{28}=\frac{77-43}{28}=\frac{17}{14}.\]

\[3:\frac{17}{14}=\frac{42}{17},\qquad \frac23:\frac32=\frac23\cdot\frac23=\frac49.\]

\[\frac{42}{17}+\frac49=\frac{378+68}{153}=\frac{446}{153}.\]

\[8:\frac{446}{153}=8\cdot\frac{153}{446}=\frac{612}{223},\qquad \frac{612}{223}+\frac{57}{223}=\frac{669}{223}=3.\]

\[5\frac57-4\frac34=\frac{40}{7}-\frac{19}{4}=\frac{160-133}{28}=\frac{27}{28},\]

\[14\cdot\frac{27}{28}=\frac{27}{2},\qquad 9\frac57=\frac{68}{7}.\]

\[\frac{27}{2}-\frac{68}{7}+\frac3{13}=\frac{351-272+6}{26}=\frac{85}{26}.\]

\[3:\frac{85}{26}=3\cdot\frac{26}{85}=\frac{78}{85}.\]

Ответ: \(\frac{78}{85}\).