2 efotue e simplefique quando possivel: a) (1)/(12)+(7)/(12) b) (2)/(9)+(1)/(6) c) (2)/(3) cdot (9)/(1) d) (3)/(10): (5)/(8)

a) \( \frac{1}{12}+\frac{7}{12} = \frac{1+7}{12} = \frac{8}{12} = \frac{2}{3} \)<br /><br />b) \( \frac{2}{9}+\frac{1}{6} = \frac{4}{18}+\frac{3}{18} = \frac{4+3}{18} = \frac{7}{18} \)<br /><br />c) \( \frac{2}{3} \cdot \frac{9}{1} = \frac{2 \cdot 9}{3 \cdot 1} = \frac{18}{3} = 6 \)<br /><br />d) \( \frac{3}{10}: \frac{5}{8} = \frac{3}{10} \cdot \frac{8}{5} = \frac{3 \cdot 8}{10 \cdot 5} = \frac{24}{50} = \frac{12}{25} \)