\[ \frac{16-7x}{(x-3)^2} - \frac{13-6x}{(3-x)^2} = \frac{16-7x}{(x-3)^2} - \frac{13-6x}{(-(x-3))^2} = \frac{16-7x}{(x-3)^2} - \frac{13-6x}{(x-3)^2} = \frac{16-7x - (13-6x)}{(x-3)^2} = \frac{16-7x-13+6x}{(x-3)^2} = \frac{3-x}{(x-3)^2} = \frac{-(x-3)}{(x-3)^2} = \frac{-1}{x-3} \]
\[ \frac{3(c^2+4)}{(c-2)^3} + \frac{12c}{(2-c)^3} = \frac{3(c^2+4)}{(c-2)^3} + \frac{12c}{(-(c-2))^3} = \frac{3(c^2+4)}{(c-2)^3} + \frac{12c}{-(c-2)^3} = \frac{3(c^2+4)}{(c-2)^3} - \frac{12c}{(c-2)^3} = \frac{3c^2+12-12c}{(c-2)^3} = \frac{3(c^2-4c+4)}{(c-2)^3} = \frac{3(c-2)^2}{(c-2)^3} = \frac{3}{c-2} \]