\begin{align*} A &= \frac{2^{1/2}}{4^{1/6}}\\
B &= \sqrt[12]{128}\vphantom{dfrac{2}{2} }\\
C &= \left( \frac{1}{8^{1/5}} \right)^2\\
D &= \sqrt{\frac{4^{-1}}{2^{-1} \cdot 8^{-1}}}\\
E &= \sqrt[3]{2^{1/2} \cdot 4^{-1/4}}.\vphantom{dfrac{2}{2}}
\end{align*}

clock

step-by-step explanation:

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18