\(\dfrac{19}{20}-y=\dfrac{8}{5}-\dfrac{3}{4}\)
\(\Leftrightarrow\dfrac{19}{20}-y=\dfrac{32-15}{20}\)
\(\Leftrightarrow\dfrac{19}{20}-y=\dfrac{17}{20}\Leftrightarrow y=\dfrac{19}{20}-\dfrac{17}{20}=\dfrac{2}{20}=\dfrac{1}{10}\)
\(y:\dfrac{2}{3}=\dfrac{4}{9}.3\)
\(\Leftrightarrow y:\dfrac{2}{3}=\dfrac{12}{9}\Leftrightarrow y=\dfrac{12}{9}.\dfrac{2}{3}=\dfrac{8}{9}\)
\(a.\dfrac{19}{20}-y=\dfrac{17}{20}\)
\(y=\dfrac{2}{17}\)
\(b.y:\dfrac{2}{3}=\dfrac{4}{3}\)
\(y=\dfrac{8}{9}\)