Đáp án + Giải thích các bước giải:
$\rm B=\dfrac{ 1+\dfrac{3}{5}-\dfrac{3}{17} } { \dfrac{-5}{3} + \dfrac{10}{34} - \dfrac{15}{25}}$
$\rm B=\dfrac{ \dfrac{8}{5}-\dfrac{3}{17} }{ \dfrac{-70}{51}-\dfrac{3}{5}}$
$\rm B=\dfrac{ \dfrac{121}{85}}{\dfrac{-503}{255}}$
$\rm B=\dfrac{121}{85} : \dfrac{-503}{255} = \dfrac{121}{85} . \dfrac{255}{-503}$
$\rm =-\dfrac{363}{503}$