\(-\dfrac{8a}{b\cdot a}=\dfrac{24}{45}\)
\(\Leftrightarrow\dfrac{-8}{b}=\dfrac{24}{45}\)
\(\Leftrightarrow b=-15\)
\(-8a=24\)
\(\Leftrightarrow a=-3\)
\(\Rightarrow A\)
\(\dfrac{-8.a}{b.a}=\dfrac{24}{45}\) (1)
⇒\(-8.a=24\)
\(a=24:-8\)
\(a=-3\) (2)
Thay (2) vào (1), ta có: \(\dfrac{-8.3}{b.3}=\dfrac{24}{45}\)
\(\dfrac{-24}{b.3}=\dfrac{24}{45}\)
⇒\(b.3=45\)
\(b=45:3\)
\(b=15\)
Chọn B