$\text{a)}x=-\left|-\frac{1}{2}\right|=-\frac{1}{2}$

$\frac{{\left(x^6:x^4\right)}^5\cdot x^2}{x\cdot x^5}=\frac{{\left(x^{6-4}\right)}^5\cdot x^2}{x^{1+5}}=\frac{{\left(x^2\right)}^5\cdot x^2}{x^6}=\frac{x^{10}\cdot x^2}{x^6}=\frac{x^{10+2}}{x^6}=\frac{x^{12}}{x^6}=x^{12-6}=x^6$  

 

$x^6={\left(-\frac{1}{2}\right)}^6=\frac{1}{64}$  

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$\text{b)}y=-\left|\frac{1}{3}\right|=-\frac{1}{3}$   

$\frac{{\left(y^4\cdot y^2\right)}^3:y^{12}}{y^2\cdot y}=\frac{{\left(y^{4+2}\right)}^3:y^{12}}{y^{2+1}}=\frac{{\left(y^6\right)}^3:y^{12}}{y^3}=\frac{y^{18}:y^{12}}{y^3}=\frac{y^{18-12}}{y^3}=\frac{y^6}{y^3}=y^{6-3}=y^3$

 

$y^3={\left(-\frac{1}{3}\right)}^3=-\frac{1}{27}$