Resolução!
[tex] \frac{x}{3} = \frac{8}{12} \\ 12x = 3 \times 8 \\12x = 24 \\ x = \frac{24}{12} \\ x = 2 \\ \\ \\ = = = = = = = = = = \\ \\ \\ \frac{2.1}{7} = \frac{x}{10} \\ 7x = 2.1 \times 10 \\ 7x = 21 \\ x = \frac{21}{7} \\ x = 3 \\ \\ \\ = = = = = = = = = = = = = = = \\ \\ \\ \frac{2}{15} = \frac{3}{2x} \\ 4x = 45 \\ x = \frac{45}{4} \\ \\ \\ = = = = = = = = = = = = = = = = = = \\ \\ \\ \frac{x + 6}{x - 6} = \frac{2}{3} \\ 3x + 18 = 2x - 12 \\ 3x - 2x = - 12 - 18 \\ x = - 30 \\ \\ \\ = = = = = = = = = = = = = = = = = \\ \\ \\ \frac{1}{5} = \frac{x - 6}{x + 1.5} \\ 5x - 30 = x + 1.5 \\ 5x - x = 1.5 + 30 \\ 4x = 31.5 \\ x = \frac{31.5}{4} \\ x = 7.875 \\ \\ \\ = = = = = = = = = = = = = = = = = = = = = \\ \\ \\ \frac{3}{4} \div \frac{1}{3} = \frac{1}{2} \div \frac{x}{} \\ \frac{3}{4} \times \frac{3}{1} = \frac{1}{2} \times \frac{1}{x} \\ \frac{9}{4} = \frac{1}{2x} \\ 18x = 4 \\ x = \frac{4 \div 2}{18 \div 2} \\ x = \frac{2}{9} \\ \\ \\ \\ \\ espero \: ter \: ajudado[/tex]
