`5/12=-x/72`
`=>30/72=-x/72`
`=>-x=30`
`=>x=-30`
Vậy `x=-30`
\(\dfrac{5}{12}=-\dfrac{x}{72}\)
\(=>-1x=\dfrac{5\cdot72}{12}=30\)
\(-1x=30\)
\(=>x=-30\)
Với \(x\in N\), ta có:
\(\dfrac{5}{12}=\dfrac{-x}{72}\)
\(\Rightarrow-12x=360\)
\(\Leftrightarrow x=-30\) (Loại)
Vậy \(x\in\varnothing\)