First you need to distribute the exponent into the terms for the first parenthesis.
(-3x²y³)³ = (-3)³ * (x²)³ * (y³)³
= -27 *x⁶ *y⁹
= -27x⁶y⁹
Then you multiply -27x⁶y⁹ by x²y.
You just need to add the exponents of x and y:
-27x⁶⁺²y⁹⁺¹
= -27x⁸y¹⁰
