Решение:

1. а) $$rac{3-2a}{2a} - rac{1-a^2}{a^2} = rac{a(3-2a) - 2(1-a^2)}{2a^2} = rac{3a - 2a^2 - 2 + 2a^2}{2a^2} = rac{3a - 2}{2a^2}$$
2. б) $$rac{1}{3x+y} - rac{1}{3x-y} = rac{(3x-y) - (3x+y)}{(3x+y)(3x-y)} = rac{3x-y - 3x -y}{(3x)^2 - y^2} = rac{-2y}{9x^2 - y^2}$$
3. в) $$rac{3}{b-2} - rac{4-3b}{b^2 - 2b} = rac{3}{b-2} - rac{4-3b}{b(b-2)} = rac{3b - (4-3b)}{b(b-2)} = rac{3b - 4 + 3b}{b(b-2)} = rac{6b - 4}{b(b-2)} = rac{2(3b - 2)}{b(b-2)}$$

Ответ: a) $$rac{3a - 2}{2a^2}$$; б) $$rac{-2y}{9x^2 - y^2}$$; в) $$rac{2(3b - 2)}{b(b-2)}$$