Вычислите: а) 15 – 16; б) -3,17 + 3,17; в) $$-1\frac{3}{14} + 2\frac{11}{21}$$; г) -379 + 948; д) -0,08 + 13; е) $$2\frac{1}{15} - 3\frac{9}{25}$$.

а) $$15 - 16 = -1$$ б) $$-3,17 + 3,17 = 0$$ в) $$-1\frac{3}{14} + 2\frac{11}{21} = -\frac{17}{14} + \frac{53}{21} = -\frac{17 \cdot 3}{14 \cdot 3} + \frac{53 \cdot 2}{21 \cdot 2} = -\frac{51}{42} + \frac{106}{42} = \frac{106 - 51}{42} = \frac{55}{42} = 1\frac{13}{42}$$ г) $$-379 + 948 = 569$$ д) $$-0,08 + 13 = 12,92$$ е) $$2\frac{1}{15} - 3\frac{9}{25} = \frac{31}{15} - \frac{84}{25} = \frac{31 \cdot 5}{15 \cdot 5} - \frac{84 \cdot 3}{25 \cdot 3} = \frac{155}{75} - \frac{252}{75} = \frac{155 - 252}{75} = -\frac{97}{75} = -1\frac{22}{75}$$