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▪228.
а) (-49 + 67) + (-37) = 18 - 37 = -19
б) (-1,4 + 0,6) + 7/15 = -0,8 + 7/15 = -4/5 + 7/15 = -12/15 + 7/15 = -5/15 = -1/3

▪229.
а) -543 + 458 = -85
б) 0,54 + (-0,83) = -0,29
в)
$- 2 \frac{5}{7} + 3 = 2 \frac{7}{7} - 2 \frac{5}{7} = \frac{2}{7}$
г)
$- \frac{2}{9} + ( - \frac{5}{6} ) = - \frac{4 + 15}{18} = - \frac{19}{18} = - 1 \frac{1}{18}$
д)
$2 \frac{9}{11} + ( - 3 \frac{7}{22} ) = 2 \frac{18}{22} - 3 \frac{7}{22} = - (1 - \frac{18 - 7 }{22} ) = - ( 1 - \frac{11}{22}) = - \frac{11}{22} = - \frac{1}{2} = - 0.5$