5.12 Раскройте скобки и решите уравнение: a) $9.8 - (7.8 - x) = 7.3$; б) $-9 + (c - 31) = -6$; в) $\frac{39}{44} - (\frac{5}{44} - x) = \frac{7}{11}$; г) $(z+5) - 21 = 5$; д) $(20 - e) + 4 = 15$; e) $(y + \frac{10}{15}) - \frac{4}{15} = 1$

a) $9.8 - (7.8 - x) = 7.3$ $9.8 - 7.8 + x = 7.3$ $2 + x = 7.3$ $x = 7.3 - 2$ $x = 5.3$ б) $-9 + (c - 31) = -6$ $-9 + c - 31 = -6$ $c - 40 = -6$ $c = -6 + 40$ $c = 34$ в) $\frac{39}{44} - (\frac{5}{44} - x) = \frac{7}{11}$ $\frac{39}{44} - \frac{5}{44} + x = \frac{28}{44}$ $\frac{34}{44} + x = \frac{28}{44}$ $x = \frac{28}{44} - \frac{34}{44}$ $x = -\frac{6}{44} = -\frac{3}{22}$ г) $(z+5) - 21 = 5$ $z + 5 - 21 = 5$ $z - 16 = 5$ $z = 5 + 16$ $z = 21$ д) $(20 - e) + 4 = 15$ $20 - e + 4 = 15$ $24 - e = 15$ $-e = 15 - 24$ $-e = -9$ $e = 9$ e) $(y + \frac{10}{15}) - \frac{4}{15} = 1$ $y + \frac{10}{15} - \frac{4}{15} = 1$ $y + \frac{6}{15} = 1$ $y = 1 - \frac{6}{15}$ $y = \frac{15}{15} - \frac{6}{15}$ $y = \frac{9}{15} = \frac{3}{5}$