2) Допиши и назови свойства вычитания числа из суммы и суммы из числа. Используя их, выполни действия устно. a – (b + c) = (a + b) – c = 18\(\frac{5}{79}\) – (17\(\frac{5}{79}\) + \(\frac{3}{4}\)) = (5\(\frac{8}{43}\) + \(\frac{7}{8}\)) – 3\(\frac{8}{43}\) =

2) Свойства вычитания:

• a – (b + c) = (a - b) - c = (a - c) - b
• (a + b) – c = (a - c) + b = a + (b - c)

18\(\frac{5}{79}\) – (17\(\frac{5}{79}\) + \(\frac{3}{4}\)) = (18\(\frac{5}{79}\) - 17\(\frac{5}{79}\)) - \(\frac{3}{4}\) = (18 - 17) + (\(\frac{5}{79}\) - \(\frac{5}{79}\)) - \(\frac{3}{4}\) = 1 - \(\frac{3}{4}\) = \(\frac{4}{4}\) - \(\frac{3}{4}\) = \(\frac{1}{4}\)

(5\(\frac{8}{43}\) + \(\frac{7}{8}\)) – 3\(\frac{8}{43}\) = (5\(\frac{8}{43}\) - 3\(\frac{8}{43}\)) + \(\frac{7}{8}\) = (5 - 3) + (\(\frac{8}{43}\) - \(\frac{8}{43}\)) + \(\frac{7}{8}\) = 2 + 0 + \(\frac{7}{8}\) = 2\(\frac{7}{8}\)

Ответ: a – (b + c) = (a - b) - c = (a - c) - b; (a + b) – c = (a - c) + b = a + (b - c); 18\(\frac{5}{79}\) – (17\(\frac{5}{79}\) + \(\frac{3}{4}\)) = \(\frac{1}{4}\); (5\(\frac{8}{43}\) + \(\frac{7}{8}\)) – 3\(\frac{8}{43}\) = 2\(\frac{7}{8}\).