\(\dfrac{-1}{24}\)-[\(\dfrac{1}{4}\)-(\(\dfrac{1}{2}\)-\(\dfrac{7}{8}\))]
=\(\dfrac{-1}{24}\)-[\(\dfrac{1}{4}\)-(\(\dfrac{4}{8}\)-\(\dfrac{7}{8}\))]
=\(\dfrac{-1}{24}\)-[\(\dfrac{1}{4}\)-\(\dfrac{-3}{8}\)]
=\(\dfrac{-1}{24}\)-[\(\dfrac{2}{8}\)-\(\dfrac{-3}{8}\)]
=\(\dfrac{-1}{24}\)-\(\dfrac{5}{8}\)
=\(\dfrac{-1}{24}\)-\(\dfrac{15}{24}\)
=\(\dfrac{-2}{3}\)