a) $$ \frac{7}{12} + (-3\frac{1}{4}) - \frac{7}{12} = \frac{7}{12} - \frac{7}{12} + (-3\frac{1}{4}) = -3\frac{1}{4} = -\frac{13}{4} = -3.25 $$
Ответ: $$-3.25$$