Упростите.
Помогите пожалуйста) Решите мне это.

A) $(frac{1}{a^2-9}:frac{b-a}{3a^2+9a}-frac{3a}{9-3b-3a+ab}):frac{3a}{b^3-27}= =(frac{1}{(a-3)(a+3)}*frac{3a(a+3)}{b-a}-frac{3a}{(a-3)(b-3)})*frac{(b-3)(b^2+3b+9)}{3a}= =frac{3a}{a-3}(frac{1}{b-a}-frac{1}{b-3})*frac{(b-3)(b^2+3b+9)}{3a}= =frac{1}{a-3}*frac{b-3-(b-a)}{(b-a)(b-3)}*(b-3)(b^2+3b+9)= =frac{b^2+3b+9}{b-a}$

б) $(1+2*frac{10y^2-3xy}{x^2-3xy})*(frac{1}{x-5y}+frac{2y}{(x-5y)^2})= =frac{x^2-3xy+20y^2-6xy}{x(x-3y)}*frac{x-5y+2y}{(x-5y)^2}= =frac{x^2-9xy+20y^2}{x(x-3y)}*frac{x-3y}{(x-5y)^2}= =frac{(x^2-10xy+25y^2)+(xy-5y^2)}{x(x-5y)^2}= =frac{(x-5y)^2+y(x-5y)}{x(x-5y)^2}= =frac{(x-5y)(x-4y)}{x(x-5y)^2}= =frac{x-4y}{x(x-5y)}$

в) $frac{1}{m^2+2mn+2n^2}-frac{1}{m^2-2mn+2n^2}-frac{m}{n(m^2+2n^2)}+frac{m}{n(m^2-2n^2)}= =frac{m^2-2mn+2n^2-(m^2+2mn+2n^2)}{((m^2+2n^2)+2mn)*((m^2+2n^2)-2mn)}-frac{m}{n}*(frac{1}{m^2+2n^2}-frac{1}{m^2-2n^2})= =-frac{4mn}{(m^2+2n^2)^2-4m^2n^2}-frac{m}{n}*frac{m^2-2n^2-(m^2+2n^2)}{m^4-4n^4}= =-frac{4mn}{m^4+4m^2n^2+4n^4-4m^2n^2}+frac{m}{n}*frac{4n^2}{m^4-4n^4}= =-frac{4mn}{m^4+4n^4}+frac{4mn}{m^4-4n^4}= =4mn*(frac{1}{m^4-4n^4}-frac{1}{m^4+4n^4})=$
$=4mn*frac{m^4+4n^4-(m^4-4n^4)}{(m^4-4n^4)(m^4+4n^4)}= =frac{32mn^5}{m^8-16n^8}$