Решите пожалуйста , заранее спасибо

1. а) $\frac{12x^{7}y^{2}}{18xy^{5}}=\frac{2x^{6}}{3y^{3}}$
б) $\frac{x^{2}-xy}{x^{2}}= \frac{x(x-y)}{x^{2}}=\frac{x-y}{x}$
в) $\frac{9a^{2}-16}{3a+4}=\frac{(3a-4)(3a+4)}{3a+4}=3a-4$
2. а) $\frac{2x}{x-2}-\frac{x}{x+2}= \frac{2x(x+2)-x(x-2)}{(x-2)(x+2)}=\frac{2x^{2}+4x-x^{2}+2x}{x^{2}-4}=\frac{x^{2}+6x}{x^{2}-4}$
б) $\frac{y}{x^{2}-xy}-\frac{1}{x-y}=\frac{y}{x(x-y)}-\frac{1}{x-y}=\frac{y-x}{x(x-y)}= \frac{-(x-y)}{x(x-y)}=-\frac{1}{x}$
в) $3b-\frac{9b}{b+3}=\frac{3b(b+3)-9b}{b+3}=\frac{3b^{2}+9b-9b}{b+3}=\frac{3b^{2}}{b+3}$
3. $\frac{8x+7}{6}-\frac{5x-2}{2}=3-\frac{3-2x}{4}$
   $12*\frac{8x+7}{6}-12*\frac{5x-2}{2}=12*3-12*\frac{3-2x}{4}$
   $2(8x+7)-6(5x-2)=36-(3-2x)$
   $16x+14-30x+12=36-9+6x$
   $-14x+26=27+6x$
   $-14x-6x=27-26$
   $-20x=1$
   $x=-0.05$
4. $\frac{3a}{a^{2}-9}-\frac{2b}{ab+3b}-\frac{b}{ab-3b}=\frac{3a}{(a-3)(a+3)}-\frac{2b}{b(a+3)}- \frac{b}{b(a-3)}=$ $\frac{3a}{(a-3)(a+3)}-\frac{2}{a+3}-\frac{1}{a-3}=\frac{3a-2(a-3)-(a+3)}{(a+3)(a-3)}= \frac{3a-2a+6-a-3}{a^{2}-9}=\frac{3}{a^{2}-9}$