Xét \(\frac{-5}{x}=\frac{-18}{72}\)

\(\Rightarrow\)(-5) . 72 = x . (-18)

\(\Rightarrow\)-360 = x . (-18)

\(\Rightarrow\)x = (-360) : (-18) = 20

Xét \(\frac{y}{16}=\frac{-18}{72}\)

\(\Rightarrow\)72y = 16 . (-18)

\(\Rightarrow\)72y = -288

\(\Rightarrow\)y = (-288) : 72 = -4

Vậy x = 20 ; y = -4

Ta có : 

   \(\frac{-5}{x}=\frac{-18}{72}\Rightarrow\frac{-5}{x}=\frac{-1}{4}\)  

                            \(\Rightarrow-5.4=x.-1\) 

                            \(\Rightarrow-20=-x\)

                            \(\Rightarrow x=20\)

Thay x = 20 vào  \(\frac{-5}{x}\)ta được : 

\(\frac{-5}{20}=\frac{y}{16}\)\(\Rightarrow\frac{-1}{4}=\frac{y}{16}\Rightarrow-1.16=y.4\)

                                                   \(\Rightarrow-16=y.4\)  

                                                    \(\Rightarrow y=-4\)  

Vậy x = 20 , y = -4

Tk mk nha !!! 

-18/72=-2/8=-4/16. Suy ra x=-4 

-5/x=-2/8.Suy ra -5.8=-2.x

-40=-2x

x=20

-18.16=72.y ( nhân chéo )

-288=72.y

y=-4

-5.16=-4(thay vào y) .x

-80=-4.x

x=20

Ta có: \(\dfrac{-5}{x}=\dfrac{-y}{8}=\dfrac{-18}{72}\)

\(\Leftrightarrow\left\{{}\begin{matrix}\dfrac{-5}{x}=-\dfrac{18}{72}=\dfrac{-1}{4}\\\dfrac{-y}{8}=\dfrac{-18}{72}=\dfrac{-1}{4}\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=20\\y=2\end{matrix}\right.\)

Vậy: (x,y)=(20;2)

\(\dfrac{-5}{x}=\dfrac{-y}{8}=\dfrac{-18}{72}\) 

+)\(\dfrac{-5}{x}=\dfrac{-18}{72}\) 

\(\Rightarrow x=\dfrac{-5.72}{-18}=20\) 

+)\(\dfrac{-y}{8}=\dfrac{-18}{72}\) 

\(\Rightarrow-y=\dfrac{-18.8}{72}=-2\) 

\(\Rightarrow y=2\)

\(\frac{-5}{x}\)=\(\frac{y}{16}\)=\(\frac{-18}{72}\)

y.72 = 16.(-18)

y = -288:72

y = -4.

x.(-4) = -5.16

x = -80:(-4)

x = 20.

Vậy x =20 ; y = -4

ta có : \(\frac{y}{16}=-\frac{18}{72}\Rightarrow-18.16=y.72\Rightarrow-288=y.72\Rightarrow y=-288:72=-4\)

\(\Rightarrow-\frac{5}{x}=-\frac{4}{16}\Rightarrow x.\left(-4\right)=-5.16\Rightarrow80:\left(-4\right)=x=>x=-20\)

vậy.....