simplify (3j^-4c^2)^3(-3j^-6c^-6)^4

$$(3j^{-4}c^2)^3(-3j^{-6}c^{-6})^4\\\\
=(3)^3(j^{-4})^3(c^2)^3(-3)^4(j^{-6})^4(c^{-6})^4\\\\
=27j^{-12}c^6\times 81j^{-24}c^{-24}\\\\
=27\times 81 j^{-36}c^{-18}\\\\
=\dfrac{2187}{j^{36}c^{18}}$$

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