Resposta:
[tex]\frac{-5}{6}+\frac{3}{4}\\ \\ \frac{-5.4+3.6}{6.4}\\ \\ \frac{-20+18}{24}\\ \\ \frac{-2}{24}\\ \\ simplificando\\ \\ \frac{-2:2}{24:2}\\ \\ \frac{-1}{12}[/tex]
b)
[tex]\frac{-5}{6}-\frac{3}{4}\\ \\ \frac{-5.4-3.6}{6.4}\\ \\ \frac{-20-18}{24}\\ \\ \frac{-38}{24}\\ \\ simplificando\\ \\ \frac{-38:2}{24:2}\\ \\ \frac{-19}{12}[/tex]
bons estudos!