a)$\frac{-1}{100}$ <0 mà $\frac{1}{101}$ >0
=>$\frac{1}{101}$ >$\frac{-1}{100}$
b)$\frac{19}{56}$ >$\frac{1}{3}$ mà $\frac{31}{94}$ <$\frac{1}{3}$
=>$\frac{19}{56}$ >$\frac{31}{94}$
<=>$\frac{-19}{56}$ <$\frac{31}{-94}$
c)$\frac{37}{147}$ >$\frac{1}{4}$ mà $\frac{51}{205}$ <$\frac{1}{4}$
=>$\frac{37}{147}$ >$\frac{51}{205}$
<=>$\frac{-37}{147}$ <$\frac{51}{-205}$
d)$\frac{3}{8}$ = $\frac{6}{18}$ mà $\frac{6}{18}$ < $\frac{6}{13}$
=>$\frac{3}{8}$< $\frac{6}{13}$
<=>$\frac{3}{-8}$> $\frac{6}{-13}$