а) 54 : (x - 7) + 22 = 31, 54 : (х - 7) = 9, х - 7 = 54/9, х - 7 = 6, х = 13. б) (29 - x) * 2 - 7 = 45, (29 - х) * 2 = 52, 29 - х = 26, х = 3. в) 3 * (x + 4) - 12 = 24, 3 * (х + 4) = 36, х + 4 = 12, х = 8. г) 45 : (17 - x) + 9 = 24, 45 : (17 - х) = 15, 17 - х = 3, х = 14.