Упрощение выражений

1. $$\frac{y+3}{2y+2} - \frac{y+1}{2y-2} + \frac{3}{y^2-1} = \frac{y+3}{2(y+1)} - \frac{y+1}{2(y-1)} + \frac{3}{(y-1)(y+1)} = \frac{(y+3)(y-1) - (y+1)(y+1) + 3\times2}{2(y+1)(y-1)} =$$ $$\frac{y^2+3y-y-3 - (y^2+2y+1) + 6}{2(y^2-1)} = \frac{y^2+2y-3 - y^2 -2y -1 + 6}{2(y^2-1)} = \frac{2}{2(y^2-1)} = \frac{1}{y^2-1}$$
2. $$\frac{3b-3c}{c} \cdot \frac{4c^2}{b^2-c^2} = \frac{3(b-c)}{c} \cdot \frac{4c^2}{(b-c)(b+c)} = \frac{3 \times 4c}{b+c} = \frac{12c}{b+c}$$
3. $$\frac{6x-30}{x+8} : \frac{x^2-25}{2x+16} = \frac{6(x-5)}{x+8} \cdot \frac{2(x+8)}{(x-5)(x+5)} = \frac{6 \times 2}{x+5} = \frac{12}{x+5}$$