Решение

• а) $$rac{12a^6b}{27a^2b^3} = \frac{4a^{6-2}}{9b^{3-1}} = \frac{4a^4}{9b^2}$$
• б) $$rac{3x^2-15x}{15x} = \frac{3x(x-5)}{15x} = \frac{x-5}{5}$$
• в) $$rac{x^2-16}{2x-8} = \frac{(x-4)(x+4)}{2(x-4)} = \frac{x+4}{2}$$