[tex]0.001y^{12}=(0.1)^3y^{4\cdot3}=(0.1)^3(y^4)^3=(0.1y^4)^3\\\\0.008b^6=(0.2)^3b^{2\cdot3}=(0.2)^3(b^2)^3=(0.2b^2)^3\\\\-\dfrac{2}{27}a^{15}=\left(-\dfrac{2}{3}\right)^3a^{5\cdot3}=\left(-\dfrac{2}{3}\right)^3(a^5)^3=\left(-\dfrac{2}{3}a^5\right)^3\\\\\text{Used:}\\\\(a^n)^m=a^{n\cdot m}\\\\(ab)^n=a^nb^n[/tex]