\(\dfrac{a}{27}=-\dfrac{5}{9}\)
\(\Rightarrow a=\dfrac{27.5}{-9}=-15\)
\(\dfrac{a}{27}=-\dfrac{45}{7}\)
\(\Rightarrow a=\dfrac{-45.27}{7}=-\dfrac{1215}{7}\)
\(\dfrac{a}{27}=\dfrac{-5}{9}=\dfrac{-45}{7}\\\rightarrow a\cdot9\cdot\left(-45\right)=27\cdot\left(-5\right)\cdot7\\ \rightarrow a\cdot9\cdot\left(-45\right)=-945\\ \rightarrow9a=\left(-945\right):\left(-45\right)\\ \rightarrow9a=21\\ \rightarrow a=\dfrac{21}{9}\)
\(=>\dfrac{a}{27}=\dfrac{-45}{7}\)
\(=>a=\left(-45.27\right):\left(7\right)=\dfrac{1215}{7}\)
mik ghi nhầm đề bài ạ
là -45/b mới đúng ạ