a) 0,01 : 25 = ( 0,75 . x ) : 0,75
\(\Rightarrow\frac{1}{2500}=0,75\cdot x:0,75\)
\(\Rightarrow x=\frac{1}{2500}\)
b) \(\left(3,8\right):\left(2x\right)=\frac{1}{4}:\frac{8}{3}\)
\(\Rightarrow3,8:\left(2x\right)=\frac{3}{32}\)
\(\Rightarrow2x=3,8:\frac{3}{32}=\frac{608}{15}\)
\(\Rightarrow x=\frac{608}{15}:2=\frac{304}{15}\)