А)(3c/a²-1/3c):(1/a+1/3c)=(9c²-a²)/3a²c:(3c+a)/3ac=(9c²-a²)(3ac)/3a²c(3c+a)=
=(3c-a)(3c+a)3ac/3a²c(3c+a)=(3c-a)/a;
б)(3a/(3a-2)+2)·(9a-6)/(9a²-4a)=(3a+2(3a-2))/(3a-2)·3(3a-2)/a(9a-4)=
=(3a+6a-4)·3(3a-2)/(3a-2)·a(9a-4)=3·(9a-4)·(3a-2)/a(3a-2)(9a-4)=3/a;
в)(a²-b²)/(x²-25)·(x+5)/(a-b)+b/(5-x)=
=(a²-b²)(x+5)/(x²-25)(a-b) +b/(5-x)=(a+b)/(x-5) +b/(5-x)=(a+b-b)/(x-5)=a/(x-5)