a) \(\dfrac{4}{x}=\dfrac{2}{9}\)
\(x=\dfrac{\left(4\times9\right)}{2}\)
\(x=\dfrac{36}{2}\)
\(x=18\)
b) \(x\times0,3=\dfrac{3}{5}\)
\(x\times\dfrac{3}{10}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:\dfrac{3}{10}\)
\(x=\dfrac{3}{5}\times\dfrac{10}{3}\)
\(x=\dfrac{30}{15}\)
\(x=2\)
c) \(1,1=\dfrac{3}{4}\) câu này thiếu
d) \(121,8:x=\dfrac{5}{9}\)
\(\dfrac{609}{5}:x=\dfrac{5}{9}\)
\(x=\dfrac{609}{5}:\dfrac{5}{9}\)
\(x=\dfrac{609}{5}\times\dfrac{9}{5}\)
\(x=\dfrac{5481}{25}\)
c) \(x:1,1=\dfrac{3}{4}\)
\(x:\dfrac{11}{10}=\dfrac{3}{4}\)
\(x=\dfrac{3}{4}\times\dfrac{11}{10}\)
\(x=\dfrac{33}{40}\)
