\(\frac{1}{30}:x:\frac{10}{15}=4\times\frac{1}{5}\)
\(\Rightarrow\frac{1}{30}:x:\frac{2}{3}=\frac{4}{5}\)
\(\Rightarrow\frac{1}{30}:x=\frac{2}{3}\times\frac{4}{5}\)
\(\Rightarrow\frac{1}{30}:x=\frac{8}{15}\)
\(\Rightarrow x=\frac{1}{30}::\frac{8}{15}\)
\(\Rightarrow x=\frac{1}{16}\)
\(\frac{1}{30}:x:\frac{10}{15}=4\cdot\frac{1}{5}\)
\(\frac{1}{30}:x:\frac{2}{3}=\frac{4}{5}\)
\(\frac{1}{30}:x=\frac{4}{5}\cdot\frac{2}{3}\)
\(\frac{1}{30}:x=\frac{8}{15}\)
\(x=\frac{1}{30}:\frac{8}{15}\)
\(x=\frac{1}{16}\)
Vậy X=\(\frac{1}{16}\)