Đáp án:
a)$\frac{5}{4}$ - $\frac{1}{2}$+ $\frac{-7}{8}$
=$\frac{5x2}{4x2}$- $\frac{1x4}{2x4}$ + $\frac{-7}{8}$
= $\frac{10}{8}$ - $\frac{4}{8} + $\frac{-7}{8}$
= $\frac{-1}{8}$
b(-$\frac{5}{24}$ + 0,75 + $\frac{7}{12}$): ( -2$\frac{1}{8}$)
= (-$\frac{5}{24}$ +$\frac{3.6}{4.6}$ + $\frac{7.2}{12.2}$) : $\frac{-15.3}{8.3}$
=(-$\frac{5}{24}$ + $\frac{18}{24}$ + $\frac{14}{24}$) : $\frac{-45}{24}$
=$\frac{9}{8}$ : $\frac{-45}{24}$
= -$\frac{3}{5}$
c)$\frac{-5}{7}$ . $\frac{2}{11}$+ $\frac{-5}{7}$. $\frac{9}{11}$+1.$\frac{5}{7}$
=$\frac{-5}{7}$.($\frac{2}{11}$ + $\frac{9}{11}$) + $\frac{5}{7}$
= $\frac{-5}{7}$ . 1 +$\frac{5}{7}$
= 0
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