Explicação passo a passo:
A) [tex]-\frac{3}{7}+\frac{1}{3}=\frac{-9+7}{21}=-\frac{2}{21}[/tex]
B) [tex]\left(-\frac{5}{6}\right)\times \left(+\frac{2}{5}\right)=-\frac{5}{6}\times \frac{2}{5}=-\frac{2}{6}=-\frac{1}{3}[/tex]
C) [tex]\left(-\frac{3}{10}\right)-\left(+\frac{1}{4}\right)=-\frac{3}{10}-\frac{1}{4}=\frac{-6-5}{20}=-\frac{11}{20}[/tex]
D) [tex]-\frac{3}{\frac{8}{\frac{2}{5}}}=\frac{\frac{3\cdot \:2}{1\cdot \:5}}{8}=-\frac{\frac{6}{5}}{8}=\frac{6}{5\cdot \:8}=-\frac{6}{40}=-\frac{3}{20}[/tex]
DA PRA VOCE VER NE VALEU FALOU
