Answer :
[tex]\frac{4}{5} \cdot x = \frac{2 }{5} \ \ /\cdot 5\\ \\ \not5^{1}\cdot \frac{4}{\not5^{1}} \cdot x =\not5^{1 } \cdot \frac{2 }{\not5^{1}}\\ \\4x=2 \ \ /:4 \\ \\x=\frac{2}{4}\\ \\x=\frac{1}{2}[/tex]
[tex]\frac{4}{5}\cdot\fbox{\ }=\frac{2}{5}\ \ \ \ /\cdot\frac{5}{4}\\\\\frac{\not5^1}{\not4_1}\cdot\frac{\not4^1}{\not5_1}\cdot\fbox{\ }=\frac{\not5^1}{\not4_2}\cdot\frac{\not2^1}{\not5_1}\\\\\fbox{\ }=\frac{1}{2}[/tex]
