3) 5. (x -0,7)-3-(-0,2). №8. Упростите выражение и приведите подобные слагаемые: a)(3,2x+10y).5-12. (4x -0,5y); 3 6)-(2,8-1,2c)+= (1,4a +2,lc); 4 2 8 6)0,2-(2,1x-2,3y) - 0,4- (3,1y+1,9x); 2) 1 (1/3m-4,5)-1½ (+5,4). №9. Решите уравнение: a) 3. (2x + 8) - (5x + 2) = 0; б)-3 (3y + 4) + 4. (2y - 1) = 0; в) 8 (3-2x) + 5. (3x + 5) = 9.

№8.

a) \[(3.2x + 10y) \cdot 5 - 12 \cdot (4x - 0.5y) = 16x + 50y - 48x + 6y = (16x - 48x) + (50y + 6y) = -32x + 56y\]

б) \(\(2.8a - 1.2c\) + \frac{3}{4} \cdot (1.4a + 2.1c) = 2.8a - 1.2c + 1.05a + 1.575c = (2.8a + 1.05a) + (-1.2c + 1.575c) = 3.85a + 0.375c\)

в) \[0.2 - (2.1x - 2.3y) - 0.4 \cdot (3.1y + 1.9x) = 0.2 - 2.1x + 2.3y - 1.24y - 0.76x = (-2.1x - 0.76x) + (2.3y - 1.24y) + 0.2 = -2.86x + 1.06y + 0.2\]

г) \[\frac{4}{15} \cdot (\frac{1}{3}m - 4.5) - 1\frac{1}{2} \cdot (\frac{8}{27}m + 5.4) = \frac{4}{45}m - \frac{4 \cdot 4.5}{15} - \frac{3}{2} \cdot \frac{8}{27}m - \frac{3}{2} \cdot 5.4 = \frac{4}{45}m - \frac{18}{15} - \frac{24}{54}m - \frac{16.2}{2} = \frac{4}{45}m - 1.2 - \frac{4}{9}m - 8.1 = \frac{4}{45}m - \frac{20}{45}m - 9.3 = -\frac{16}{45}m - 9.3\]

№9.

a) \[3 \cdot (2x + 8) - (5x + 2) = 0 \Rightarrow 6x + 24 - 5x - 2 = 0 \Rightarrow x + 22 = 0 \Rightarrow x = -22\]

б) \[-3 \cdot (3y + 4) + 4 \cdot (2y - 1) = 0 \Rightarrow -9y - 12 + 8y - 4 = 0 \Rightarrow -y - 16 = 0 \Rightarrow y = -16\]

в) \[8 \cdot (3 - 2x) + 5 \cdot (3x + 5) = 9 \Rightarrow 24 - 16x + 15x + 25 = 9 \Rightarrow -x + 49 = 9 \Rightarrow -x = -40 \Rightarrow x = 40\]