\(\frac{-1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)
\(\frac{-1}{24}-\left(\frac{1}{4}+\frac{3}{8}\right)\)
\(\frac{-1}{24}-\frac{5}{8}\)
\(\frac{-2}{3}\)
\(-\frac{1}{24}-\left[\frac{1}{4}-\left(\frac{1}{2}-\frac{7}{8}\right)\right]\)
\(=-\frac{1}{24}-\left(\frac{1}{4}-\frac{1}{2}+\frac{7}{8}\right)\)
\(=-\frac{1}{24}-\frac{5}{8}\)
\(=-\frac{1}{24}-\frac{15}{24}\)
\(=-\frac{16}{24}=-\frac{2}{3}\)