Câu 1 :
a) -$\frac{3}{5}$ > -$\frac{4}{5}$
b) $\frac{4}{-5}$ > $\frac{9}{-10}$
Câu 2:
a) $\frac{4}{5}$ + ( -$\frac{5}{6}$ )
= $\frac{4.6}{5.6}$ + ( -$\frac{5.5}{6.5}$ )
= $\frac{24}{30}$ + -$\frac{25}{30}$
= -$\frac{1}{30}$
b) $\frac{5}{9}$ . $\frac{4}{-7}$
= $\frac{5.4}{9.(-7)}$
= $\frac{20}{-63}$
c) 5$\frac{2}{3}$ . $\frac{9}{7}$ - $\frac{17}{7}$ . $\frac{2}{3}$
= $\frac{17}{3}$ . $\frac{9}{7}$ - $\frac{17}{7}$ . $\frac{2}{3}$
= $\frac{17.9}{3.7}$ - $\frac{17.2}{7.3}$
= $\frac{153}{21}$ - $\frac{34}{21}$
= $\frac{119}{21}$
= $\frac{17}{3}$
Câu 3:
a) x + $\frac{1}{3}$ = -$\frac{1}{5}$
x = -$\frac{1}{5}$ - $\frac{1}{3}$
x = -$\frac{3}{15}$ - $\frac{5}{15}$
x = -$\frac{8}{15}$