a) \(\frac{1}{3} + \frac{3}{4} - \frac{5}{6}\)

\(= \frac{4}{12} + \frac{9}{12} - \frac{10}{12}\)

\(= \frac{4 + 9 - 10}{12}\)

\(= \frac{3}{12}\)

\(= \frac{1}{4}\).

b) \(\frac{- 2}{3} + \frac{6}{5} : \frac{2}{3} - \frac{2}{15}\)

\(= \frac{- 2}{3} + \frac{6}{5} . \frac{3}{2} - \frac{2}{15}\)

\(= \frac{- 2}{3} + \frac{18}{10} - \frac{2}{15}\)

\(= \frac{- 2}{3} + \frac{9}{5} - \frac{2}{15}\)

\(= \frac{- 10}{15} + \frac{27}{15} - \frac{2}{15}\)

\(= \frac{15}{15} = 1\).

c) \(\frac{- 3}{7} + \frac{5}{13} + \frac{- 4}{7}\)

\(= \left(\right. \frac{- 3}{7} + \frac{- 4}{7} \left.\right) + \frac{5}{13}\)

\(= \frac{- 7}{7} + \frac{5}{13}\)

\(= - 1 + \frac{5}{13}\)

\(= \frac{- 8}{13}\).

d) \(\frac{12}{19} + \frac{- 8}{13} - \frac{12}{19} + \frac{5}{- 13} + 2\)

\(= \frac{12}{19} + \frac{- 8}{13} - \frac{12}{19} + \frac{- 5}{13} + 2\)

\(= \left(\right. \frac{12}{19} - \frac{12}{19} \left.\right) + \left(\right. \frac{- 8}{13} + \frac{- 5}{13} \left.\right) + 2\)

\(= 0 + \frac{- 13}{13} + 2\)

\(= 1\).

 −38=−924;5−12=−1012

a, 6700

b, 27.334

a, vi ; xxiv ; xxxix

b, 36 = 36; 18; 12; 9

a, 320 , 4914 , 90

b, 2315 , 320

c, 4914 , 90 , 543

d, 90