5.282 Вычислите значение выражения: a) 14 9/13 - 1 5/13 + 12 11/13 б) 17 7/40 + 3 9/40 - 1 17/40

a) $$14\frac{9}{13} - 1\frac{5}{13} + 12\frac{11}{13} = (14-1+12) + (\frac{9}{13} - \frac{5}{13} + \frac{11}{13}) = 25 + \frac{15}{13} = 25 + 1\frac{2}{13} = 26\frac{2}{13}$$; б) $$17\frac{7}{40} + 3\frac{9}{40} - 1\frac{17}{40} = (17+3-1) + (\frac{7}{40} + \frac{9}{40} - \frac{17}{40}) = 19 + \frac{-1}{40} = 19 - \frac{1}{40} = 18 + 1 - \frac{1}{40} = 18 + \frac{40}{40} - \frac{1}{40} = 18 + \frac{39}{40} = 18\frac{39}{40}$$