190. a) 1\frac{2}{3}x + \frac{5}{6}x = 2\frac{1}{2} + \frac{7}{12} - 4\frac{1}{4}

1. Convert mixed numbers to improper fractions: \(\frac{5}{3}x + \frac{5}{6}x = \frac{5}{2} + \frac{7}{12} - \frac{17}{4}\).
2. Combine like terms: \(\frac{10x + 5x}{6} = \frac{30 + 7 - 51}{12}\) which simplifies to \(\frac{15x}{6} = \frac{-14}{12}\).
3. Solve for x: \(\frac{5}{2}x = -\frac{7}{6}\) => \(x = -\frac{7}{6} \times \frac{2}{5} = -\frac{7}{15}\).