a) \(2,5:2,7=x:\frac{3}{5}\)
\(\Rightarrow\frac{5}{2}:\frac{27}{10}=x.\frac{5}{3}\)
\(\Rightarrow\frac{5}{2}.\frac{10}{27}=\frac{5x}{3}\)
\(\Rightarrow\frac{25}{27}=\frac{5x}{3}\)
\(\Rightarrow5x=\frac{25.3}{27}=\frac{75}{27}=\frac{25}{9}\)
\(\Rightarrow x=\frac{25}{9}:5=\frac{25}{9}.\frac{1}{5}=\frac{5}{9}\)
b) \(\frac{19}{5}:\frac{608}{15}=0,25:x\)
\(\Rightarrow\frac{19}{5}.\frac{15}{608}=\frac{1}{4}:x\)
\(\Rightarrow\frac{3}{32}=\frac{1}{4}:x\)
\(\Rightarrow x=\frac{1}{4}:\frac{3}{32}=\frac{1}{4}.\frac{32}{3}=\frac{8}{3}\)
c/ \(\frac{8}{3}:x=\frac{16}{9}:0,2\)
\(\Rightarrow\frac{8}{3}:x=\frac{16}{9}:\frac{1}{5}=\frac{16}{9}.5=\frac{80}{9}\)
\(\Rightarrow x=\frac{8}{3}:\frac{80}{9}=\frac{8}{3}.\frac{9}{80}=\frac{3}{10}\)