Bài 1: \(\dfrac{36}{72}=\dfrac{1}{2}\);\(\dfrac{-28}{70}=\dfrac{-2}{5}\);\(\dfrac{-54}{102}=\dfrac{-9}{17}\);\(\dfrac{45}{-130}=\dfrac{-9}{26}\)
Bài 3:
a: \(\dfrac{x}{5}=\dfrac{-16}{60}\)
\(\Leftrightarrow x=\dfrac{-16\cdot5}{60}=\dfrac{-80}{60}=-\dfrac{4}{3}\)
b: 25/x=5/-2
\(\Leftrightarrow x=\dfrac{-2\cdot25}{5}=-2\cdot5=-10\)
c: \(\dfrac{x}{3}=\dfrac{-20}{y}=\dfrac{-1}{3}\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=\dfrac{3\cdot\left(-1\right)}{3}=-1\\y=\dfrac{-20\cdot3}{-1}=60\end{matrix}\right.\)
d: \(\dfrac{-4}{x}=\dfrac{3}{y}=\dfrac{-1}{2}\)
\(\Leftrightarrow\left\{{}\begin{matrix}x=-4\cdot\dfrac{2}{-1}=8\\y=\dfrac{3\cdot2}{-1}=-6\end{matrix}\right.\)
