Răspuns :
[tex] \frac{6}{x} = \frac{2}{5} \\ \\ 6 = \frac{2}{5}x \\ \\ 6 = \frac{2x}{5} \\ \\ 6 \times 5 = 2x \\ \\ 30 = 2x \\ \\ \frac{30}{2} = x \\ \\ 15 = x \\ \\ x = 15 [/tex]
[tex] \frac{6}{x} = \frac{2}{5} \\ \\ 6 = \frac{2}{5}x \\ \\ 6 = \frac{2x}{5} \\ \\ 6 \times 5 = 2x \\ \\ 30 = 2x \\ \\ \frac{30}{2} = x \\ \\ 15 = x \\ \\ x = 15 [/tex]