Resposta:
a)[tex]\frac{169}{240}[/tex]
b)[tex]\frac{17}{12}[/tex]
Explicação passo a passo:
a)
[tex]\left\{\frac{1}{2}+\left[\left(\frac{2}{3}-\frac{1}{5}\right)\cdot \frac{7}{8}\right]\right\}\\\\\left\{\frac{1}{2}+\left[\frac{7}{15}\cdot \frac{7}{8}\right]\right\}\\\\\left\{\frac{1}{2}+\frac{49}{120}\right\}\\\\\frac{169}{240}[/tex]
b)
[tex]-\frac{4}{5}+\left[-\frac{6}{5}+\left(\frac{2}{3}+\frac{11}{4}\right)\right]\\\\-\frac{4}{5}+\left[-\frac{6}{5}+\frac{41}{12}\right]\\\\-\frac{4}{5}+\frac{133}{60}\\\\\frac{425^{\div5}}{300^{\div5}}=\frac{85^{\div5}}{60^{\div5}}=\frac{17}{12}[/tex]
