(6xy^-3)^-3 * 36x^4 / x^-4 y

Step 1: Apply the exponent -3 to each term inside the first parenthesis: (6^-3 * x^-3 * y^9).

Step 2: Simplify the expression: (1/216 * x^-3 * y^9) * 36x^4 / x^-4 y.

Step 3: Combine terms: (36/216) * (x^-3 * x^4) * (y^9 / y) * x^4 = (1/6) * x * y^8 * x^4 = (1/6) * x^5 * y^8.