181. Найдите значение выражения: 1)-53 +61-48 + 71; 2) 3,17 – 5,9 – 0,87; 3) -0,96 + (-5,37) – (-1,02) + 6,3; 4) -19,23 - 15,88 – (-21,34) + (−11,08); 5) 5\frac{3}{7}+(-2\frac{2}{3})-(-3\frac{8}{21}); 6) 2\frac{5}{6}+(-3\frac{7}{8})-(-2\frac{1}{12})-1\frac{2}{3}.

Ответы: 1) 31; 2) -3,6; 3) 0,99; 4) -24,85; 5) 6\frac{13}{21}; 6) -\frac{11}{8} = -1\frac{3}{8}

1. -53 + 61 - 48 + 71 = (61 + 71) - (53 + 48) = 132 - 101 = 31

2. 3,17 - 5,9 - 0,87 = 3,17 - (5,9 + 0,87) = 3,17 - 6,77 = -3,6

3. -0,96 + (-5,37) - (-1,02) + 6,3 = -0,96 - 5,37 + 1,02 + 6,3 = (6,3 + 1,02) - (0,96 + 5,37) = 7,32 - 6,33 = 0,99

4. -19,23 - 15,88 - (-21,34) + (-11,08) = -19,23 - 15,88 + 21,34 - 11,08 = 21,34 - (19,23 + 15,88 + 11,08) = 21,34 - 46,19 = -24,85

5. 5\frac{3}{7} + (-2\frac{2}{3}) - (-3\frac{8}{21}) = 5\frac{3}{7} - 2\frac{2}{3} + 3\frac{8}{21} = 5\frac{9}{21} - 2\frac{14}{21} + 3\frac{8}{21} = (5 - 2 + 3) + (\frac{9}{21} - \frac{14}{21} + \frac{8}{21}) = 6 + \frac{9 - 14 + 8}{21} = 6 + \frac{3}{21} = 6 + \frac{1}{7} = 6\frac{1}{7}

6. 2\frac{5}{6} + (-3\frac{7}{8}) - (-2\frac{1}{12}) - 1\frac{2}{3} = 2\frac{5}{6} - 3\frac{7}{8} + 2\frac{1}{12} - 1\frac{2}{3} = (2 - 3 + 2 - 1) + (\frac{5}{6} - \frac{7}{8} + \frac{1}{12} - \frac{2}{3}) = 0 + (\frac{5 \cdot 4}{6 \cdot 4} - \frac{7 \cdot 3}{8 \cdot 3} + \frac{1 \cdot 2}{12 \cdot 2} - \frac{2 \cdot 8}{3 \cdot 8}) = \frac{20}{24} - \frac{21}{24} + \frac{2}{24} - \frac{16}{24} = \frac{20 - 21 + 2 - 16}{24} = \frac{-15}{24} = -\frac{5}{8}

Ответы: 1) 31; 2) -3,6; 3) 0,99; 4) -24,85; 5) 6\frac{1}{7}; 6) -\frac{5}{8}