a) 27a - (1/9)a = (1/3)a -

1. Combine like terms: $$27a - \frac{1}{9}a = \frac{243a - a}{9} = \frac{242a}{9}$$.
2. The expression is $$27a - \frac{1}{9}a = \frac{1}{3}a - x$$.
3. $$\frac{242a}{9} = \frac{1}{3}a - x$$.
4. $$x = \frac{1}{3}a - \frac{242a}{9} = \frac{3a - 242a}{9} = \frac{-239a}{9}$$.