Номер 5. Найдите значение выражения: а) 2,5 - 8,5; б) -7,62 - (-7,24); в) 3,9 - (-2,3); г) 5/12 - (-1/12); д) 4/9 * 2/3;

Решим задания из номера 5: a) $2,5 - 8,5 = -6$ б) $-7,62 - (-7,24) = -7,62 + 7,24 = -0,38$ в) $3,9 - (-2,3) = 3,9 + 2,3 = 6,2$ г) $\frac{5}{12} - (-\frac{1}{12}) = \frac{5}{12} + \frac{1}{12} = \frac{6}{12} = 0,5$ д) $\frac{4}{9} \cdot \frac{2}{3} = \frac{8}{27}$ е) $-1\frac{3}{8} \cdot \frac{1}{4} = -\frac{11}{8} \cdot \frac{1}{4} = -\frac{11}{32}$ ж) $1\frac{5}{11} \cdot 2\frac{3}{22} = \frac{16}{11} \cdot \frac{47}{22} = \frac{8 \cdot 47}{11 \cdot 11} = \frac{376}{121} = 3\frac{13}{121}$ з) $3,8 + (-8,9) = 3,8 - 8,9 = -5,1$ и) $\frac{2}{3} + \frac{5}{6} = \frac{4}{6} + \frac{5}{6} = \frac{9}{6} = 1,5$ к) $7 \cdot (-4,9) = -34,3$ л) $-5 - (-2,9) = -5 + 2,9 = -2,1$ м) $-3\frac{1}{2} - (-1\frac{3}{4}) = -3,5 + 1,75 = -1,75$ н) $-3,2 \cdot 2\frac{1}{3} = -\frac{32}{10} \cdot \frac{7}{3} = -\frac{16}{5} \cdot \frac{7}{3} = -\frac{112}{15} = -7\frac{7}{15}$ о) $(3\frac{7}{30} - 1\frac{5}{12}) : 18\frac{1}{6} = (3\frac{14}{60} - 1\frac{25}{60}) : \frac{109}{6} = (2\frac{74}{60} - 1\frac{25}{60}) : \frac{109}{6} = 1\frac{49}{60} : \frac{109}{6} = \frac{109}{60} \cdot \frac{6}{109} = \frac{1}{10} = 0,1$ п) $(1\frac{1}{2} + 2\frac{2}{3}) : 1\frac{1}{3} = (1\frac{3}{6} + 2\frac{4}{6}) : \frac{4}{3} = 3\frac{7}{6} : \frac{4}{3} = 4\frac{1}{6} : \frac{4}{3} = \frac{25}{6} \cdot \frac{3}{4} = \frac{25}{8} = 3,125$ р) $(1\frac{11}{18} - 1\frac{7}{12}) : (2\frac{1}{6} + \frac{7}{30}) = (1\frac{22}{36} - 1\frac{21}{36}) : (2\frac{5}{30} + \frac{7}{30}) = \frac{1}{36} : 2\frac{12}{30} = \frac{1}{36} : 2\frac{2}{5} = \frac{1}{36} : \frac{12}{5} = \frac{1}{36} \cdot \frac{5}{12} = \frac{5}{432}$ с) $(2\frac{3}{5} - 5) \cdot (\frac{31}{48} + \frac{7}{24}) = (2\frac{3}{5} - 4\frac{5}{5}) \cdot (\frac{31}{48} + \frac{14}{48}) = -2\frac{2}{5} \cdot \frac{45}{48} = -\frac{12}{5} \cdot \frac{15}{16} = -\frac{3}{1} \cdot \frac{3}{4} = -\frac{9}{4} = -2,25$