Explicação passo-a-passo:
[tex] \frac{x}{3} = \frac{8}{12} \\ 12x = 24 \\ x = \frac{24}{12} \\ x = 2[/tex]
[tex] \frac{10}{7} = \frac{x}{21} \\ 7x = 210 \\ x = \frac{210}{7} \\ x = 30[/tex]
[tex] \frac{2x}{3} = \frac{16}{2} \\ 4x = 48 \\ x = \frac{48}{4} \\ x = 12[/tex]
