РЕШИТЬ ПРОСТЕНЬКИЕ ПРИМЕРЫ.ДАЮ 57 БАЛЛОВ!!!

Решите задачу:

$1)(\frac{12x}{4x^{2}-9}+ \frac{3}{3-2x}):(1- \frac{2x-3}{2x+3})=( \frac{12x}{(2x-3)(2x+3)}- \frac{3}{2x-3})* \frac{2x+3}{2x+3-2x+3}= \frac{12x-6x-9}{(2x-3)(2x+3)}* \frac{2x+3}{6}= \frac{6x-9}{2x-3}* \frac{1}{6}= \frac{3(2x-3)}{2x-3}* \frac{1}{6} =0,5$

$2)(\frac{a+b}{b}- \frac{a}{a+b}):( \frac{a+b}{a}- \frac{b}{a+b})= \frac{a^{2}+2ab+b^{2}-ab}{b(a+b)}: \frac{a^{2}+2ab+b^{2}-ab}{a(a+b)}= \frac{a^{2}+ab+b^{2}}{b(a+b)}* \frac{a(a+b)}{a^{2}+ab+b^{2}}= \frac{a}{b}$

$3)(1-\frac{3x^{2}} {1-x^{2}}):( \frac{x}{x+1}+1)= \frac{1-x^{2}-3x^{2}} {1-x^{2}}: \frac{x+x+1}{x+1}= \frac{1-4x^{2}} {1-x^{2}}* \frac{x+1}{2x+1}= \frac{(1-2x)(1+2x)}{(1-x)(1+x)}* \frac{x+1}{2x+1}= \frac{1-2x}{1-x}$