10.Раскройте скобки и упростите выражения (приведите подобные):

### 10. Раскройте скобки и упростите выражения: а) $2x - (2x + y) + y = 2x - 2x - y + y = 0$ б) $-a + (2a - b) + 2b = -a + 2a - b + 2b = a + b$ в) $7 - (c + 14) - 2c = 7 - c - 14 - 2c = -3c - 7$ г) $3y - (18 + y) + 8 = 3y - 18 - y + 8 = 2y - 10$ д) $-(7 - x) + (3x - 14) = -7 + x + 3x - 14 = 4x - 21$ е) $-(x + 4) - (2x - 8) = -x - 4 - 2x + 8 = -3x + 4$ ё) $(21 - a) - (20 - 2a) = 21 - a - 20 + 2a = a + 1$ ж) $-(13 + c) + (-c - 13) = -13 - c - c - 13 = -2c - 26$ з) $2(3 - x) - (8 + x) = 6 - 2x - 8 - x = -3x - 2$ и) $-4(y + 5) + (12 - y) = -4y - 20 + 12 - y = -5y - 8$ й) $-(7 - x) + 4(x - 5) = -7 + x + 4x - 20 = 5x - 27$ к) $-9(y - 4) - (12 + y) = -9y + 36 - 12 - y = -10y + 24$ ### 11. Решить уравнения: а) $9\frac{16}{51} + 2x = 4\frac{11}{34} \implies 2x = 4\frac{11}{34} - 9\frac{16}{51}$. Приведем к общему знаменателю $102$: $4\frac{33}{102} - 9\frac{32}{102} = -5\frac{-1}{102} = -4\frac{101}{102} \implies x = -2\frac{101}{204}$ б) $3z + 2\frac{11}{52} = 7\frac{5}{39} \implies 3z = 7\frac{5}{39} - 2\frac{11}{52} = 7\frac{20}{156} - 2\frac{33}{156} = 6\frac{176}{156} - 2\frac{33}{156} = 4\frac{143}{156} = 4\frac{11}{12} \implies z = \frac{59}{12} : 3 = \frac{59}{36} = 1\frac{23}{36}$ в) $0,2(5y - 2) - 0,3(2y - 1) = -0,9 \implies y - 0,4 - 0,6y + 0,3 = -0,9 \implies 0,4y = -0,9 + 0,1 \implies 0,4y = -0,8 \implies y = -2$ г) $0,3(5x - 7) - 3(0,2x + 3,2) = 0 \implies 1,5x - 2,1 - 0,6x - 9,6 = 0 \implies 0,9x = 11,7 \implies x = 13$ д) $3(0,4x + 7) - 4(0,8x - 3) = 2 \implies 1,2x + 21 - 3,2x + 12 = 2 \implies -2x = 2 - 33 \implies -2x = -31 \implies x = 15,5$ е) $0,7x - 1,82 - 0,8x = 3,46 \implies -0,1x = 5,28 \implies x = -52,8$ ё) $-8\frac{7}{39} - 3x = 5\frac{9}{26} \implies -3x = 5\frac{9}{26} + 8\frac{7}{39} = 5\frac{27}{78} + 8\frac{14}{78} = 13\frac{41}{78} \implies x = -\frac{1055}{78} : 3 = -\frac{1055}{234} = -4\frac{119}{234}$ ж) $\frac{1}{7}x + \frac{3}{14}x = 14 \implies \frac{2}{14}x + \frac{3}{14}x = 14 \implies \frac{5}{14}x = 14 \implies x = 14 \cdot \frac{14}{5} = \frac{196}{5} = 39,2$ з) $3,6 + 2x - 5x = 1,2 \implies -3x = 1,2 - 3,6 \implies -3x = -2,4 \implies x = 0,8$ и) $4,72 - 2,5x - 2x = 2,92 \implies -4,5x = 2,92 - 4,72 \implies -4,5x = -1,8 \implies x = 0,4$ к) $4(1 - 0,5a) + 2(3 + 2a) = 0 \implies 4 - 2a + 6 + 4a = 0 \implies 2a = -10 \implies a = -5$ л) $4(3 - 2x) - 2(3 + 2x) = -24 \implies 12 - 8x - 6 - 4x = -24 \implies -12x = -24 - 6 \implies -12x = -30 \implies x = 2,5$