a) Ta có: \(\frac{7}{8}+\frac{15}{23}+\frac{1}{8}+\left(-\frac{15}{23}\right)+\frac{1}{3}\)
\(=\left(\frac{7}{8}+\frac{1}{8}\right)+\left(\frac{15}{23}-\frac{15}{23}\right)+\frac{1}{3}\)
\(=1+\frac{1}{3}=\frac{4}{3}\)
b) Ta có: \(\frac{3-\frac{2}{3}}{\frac{1}{3}-3}\)
\(=\left(3-\frac{2}{3}\right)\cdot\frac{1}{\frac{1}{3}-3}=\left(3-\frac{2}{3}\right)\cdot\frac{1}{-\frac{8}{3}}\)
\(=\left(3-\frac{2}{3}\right)\cdot\frac{-3}{8}\)
\(=-\frac{9}{8}+\frac{1}{4}=\frac{-9}{8}+\frac{2}{8}=-\frac{7}{8}\)
c) Ta có: \(8\cdot\left(-\frac{1}{2}\right)^3+3\cdot\left(-\frac{1}{2}\right)^2-0,75\)
\(=8\cdot\frac{-1}{8}+3\cdot\frac{1}{4}-\frac{3}{4}\)
\(=-1\)