\(\dfrac{a}{b}=\dfrac{-0,5}{-0,15}=\dfrac{0,5}{0,15}=\dfrac{50}{15}=\dfrac{10}{3}\)
Ta có:a=-0,5= -\(\dfrac{1}{2}\)
Ta có:b=-0,15=-\(\dfrac{3}{20}\)
\(\Rightarrow\)a:b=(-\(\dfrac{1}{2}\)):(-\(\dfrac{3}{20}\))=\(\dfrac{1}{2}\):\(\dfrac{3}{20}\)=\(\dfrac{1}{2}\)x\(\dfrac{20}{3}\)=\(\dfrac{10}{3}\)