2. Найдите значение выражения: a) -29 + 12 + (-40) + (-31) + 38; б) 6/13 * 4 * 5/6 * 13/6; в) -11/15 * 4.2 - 4.2 * 4/15.

a) -29 + 12 + (-40) + (-31) + 38 = -29 + 12 - 40 - 31 + 38 = -17 - 40 - 31 + 38 = -57 - 31 + 38 = -88 + 38 = -50 б) $$\frac{6}{13} * 4 * \frac{5}{6} * \frac{13}{6} = \frac{6 * 4 * 5 * 13}{13 * 6 * 6} = \frac{4 * 5}{6} = \frac{20}{6} = \frac{10}{3} = 3\frac{1}{3}$$ в) $$-\frac{11}{15} * 4.2 - 4.2 * \frac{4}{15} = 4.2 * (-\frac{11}{15} - \frac{4}{15}) = 4.2 * (-\frac{15}{15}) = 4.2 * (-1) = -4.2$$