17. Найдите значение выражения 5/6 + 7/12 : 7/2.

17. $\frac{5}{6} + \frac{7}{12} : \frac{7}{2} = \frac{5}{6} + \frac{7}{12} \cdot \frac{2}{7} = \frac{5}{6} + \frac{1}{6} = \frac{6}{6} = 1$. 18. $\frac{7,8 + 8,3}{4,6} = \frac{16,1}{4,6} = 3,5$. 19. $7,5 \cdot 3,6 - 2,5 = 27 - 2,5 = 24,5$. 20. $\frac{12}{7} : (\frac{5}{14} - \frac{2}{7}) = \frac{12}{7} : (\frac{5}{14} - \frac{4}{14}) = \frac{12}{7} : \frac{1}{14} = \frac{12}{7} \cdot 14 = 24$. 21. $-x = 4 - 3(3x - 8) \Rightarrow -x = 4 - 9x + 24 \Rightarrow 8x = 28 \Rightarrow x = 3,5$. 22. $3x - 4 = 7x + 6 \Rightarrow -4x = 10 \Rightarrow x = -2,5$. 23. $15 - 4(7 - x) = 11 \Rightarrow 15 - 28 + 4x = 11 \Rightarrow 4x - 13 = 11 \Rightarrow 4x = 24 \Rightarrow x = 6$. 24. $-2x = 7 - 3(3x - 7) \Rightarrow -2x = 7 - 9x + 21 \Rightarrow 7x = 28 \Rightarrow x = 4$. 25. $25 - 4(11 - x) = 13 \Rightarrow 25 - 44 + 4x = 13 \Rightarrow 4x - 19 = 13 \Rightarrow 4x = 32 \Rightarrow x = 8$. 26. $2 - 3(2 + 3x) = 14 \Rightarrow 2 - 6 - 9x = 14 \Rightarrow -9x - 4 = 14 \Rightarrow -9x = 18 \Rightarrow x = -2$. 27. $7 - 4(6x - 2) = 3 \Rightarrow 7 - 24x + 8 = 3 \Rightarrow -24x + 15 = 3 \Rightarrow -24x = -12 \Rightarrow x = 0,5$. 28. $(7x - 8) - (2x - 5) = 17 \Rightarrow 7x - 8 - 2x + 5 = 17 \Rightarrow 5x - 3 = 17 \Rightarrow 5x = 20 \Rightarrow x = 4$. 29. $2x - 3(x - 3) = 12 \Rightarrow 2x - 3x + 9 = 12 \Rightarrow -x = 3 \Rightarrow x = -3$. 30. $5(x - 3) + 7 - 2x = 16 \Rightarrow 5x - 15 + 7 - 2x = 16 \Rightarrow 3x - 8 = 16 \Rightarrow 3x = 24 \Rightarrow x = 8$. 31. $8 - 5(8 + 3x) = 13 \Rightarrow 8 - 40 - 15x = 13 \Rightarrow -15x - 32 = 13 \Rightarrow -15x = 45 \Rightarrow x = -3$. 32. $12 - 8(4 - x) = 4 \Rightarrow 12 - 32 + 8x = 4 \Rightarrow 8x - 20 = 4 \Rightarrow 8x = 24 \Rightarrow x = 3$. 33. $11 - 5(4x - 3) = 4 \Rightarrow 11 - 20x + 15 = 4 \Rightarrow -20x + 26 = 4 \Rightarrow -20x = -22 \Rightarrow x = 1,1$. 34. $3x - 2(3x - 2) = 19 \Rightarrow 3x - 6x + 4 = 19 \Rightarrow -3x = 15 \Rightarrow x = -5$. 35. $5(x - 2,4) = 13x \Rightarrow 5x - 12 = 13x \Rightarrow -8x = 12 \Rightarrow x = -1,5$. 36. $8x - 18 = 6x - 2(x - 5) \Rightarrow 8x - 18 = 6x - 2x + 10 \Rightarrow 8x - 18 = 4x + 10 \Rightarrow 4x = 28 \Rightarrow x = 7$. 37. $3x - 2(3x + 4) = 10 \Rightarrow 3x - 6x - 8 = 10 \Rightarrow -3x = 18 \Rightarrow x = -6$. 38. $-5x = 11 - 2(4x - 2) \Rightarrow -5x = 11 - 8x + 4 \Rightarrow 3x = 15 \Rightarrow x = 5$. 39. $3x - 11 = 6x - 4(2x - 1) \Rightarrow 3x - 11 = 6x - 8x + 4 \Rightarrow 3x - 11 = -2x + 4 \Rightarrow 5x = 15 \Rightarrow x = 3$. 40. $2(4 + 3x) = -x - 13 \Rightarrow 8 + 6x = -x - 13 \Rightarrow 7x = -21 \Rightarrow x = -3$.