[tex] \frac{8}{213} + \frac{2}{213} - \frac{1}{12} - \frac{9}{213} = \frac{8}{213} + \frac{2}{213} - \frac{1}{12} - \frac{3}{71} = \frac{8 \times 4}{213 \times 4} + \frac{2 \times 4}{213 \times 4} - \frac{1 \times 71}{12 \times 71} - \frac{3 \times 12}{71 \times 12} = \frac{32}{852} + \frac{8}{852} - \frac{71}{852} - \frac{36}{852} = \frac{32 + 8 - 71 - 36}{852} = \frac{ - 67}{852} = - \frac{67}{852} [/tex]
