[tex] \frac{ \frac{2}{5} }{x} = \frac{ \frac{1}{4} }{10} [/tex]
[tex] \frac{1}{4} \times x = \frac{2}{5} \times 10[/tex]
[tex] \frac{x}{4} = \frac{2 \times 10}{5} [/tex]
[tex] \frac{x}{4} = \frac{20}{5} [/tex]
[tex] \frac{x}{4} = 4[/tex]
[tex]x = \frac{4 \times 4}{1} [/tex]
[tex]x = 16[/tex]