а)2m-(2m+6)+(5m-3)
b)x+5y-9x-17y-11x
c)1.9x-6.7y-3x

1/2 +  (3m * ( 1+3m) +2m * (1 -3m))/ (1-9m^2) * (3m-1)^2 / (2m*(3m+5) =1/2 + (3m+9m^2+2m-6m^2)/(1-9m^2) * (3m-1)^2 /2m(3m+5) =1/2 + (5m+3m^2)/ (1-9m^2) * (3m-1)^2 / 2m (3m+5) =1/2 + (m*95+3m)*(3m-1)^2 )/ (2m(3m+5)*(1-9m^2) =1/2+(3m-1)^2 / (-2 *( 3m-1)(1+3m))= 1/2+ (3m-1)/(-2(1+3m)) = (-(1+3m)+3m-1))/(-2(1+3m)) = (-2)/(-2(1+3m) = 1/ (1+3m)