a: \(\dfrac{18}{91}< \dfrac{18}{90}=\dfrac{1}{5};\dfrac{23}{114}>\dfrac{23}{115}=\dfrac{1}{5}\)
Do đó: \(\dfrac{18}{91}< \dfrac{23}{114}\)
=>\(-\dfrac{18}{91}>-\dfrac{23}{114}\)
b: \(\dfrac{22}{35}>\dfrac{21}{35}=0,6;\dfrac{103}{177}< \dfrac{106,2}{177}=0,6\)
Do đó: \(\dfrac{22}{35}>\dfrac{103}{177}\)
=>\(-\dfrac{22}{35}< -\dfrac{103}{177}\)