1. You distribute the exponent 3 to all the integers and variables inside the paranthesis.

2. After that, you will notice there is x^-3 on the denominator. Following the rules on tigonometry regarding negative exponents on functions of variables, you put it on the numerator side changing it to positive, You will now have an equation of 64y^3x^15x^3/y^4.

3. You now add the exponents of x (The Power Rule. It means that when you have x^mx^n, you simply have it to x^m+n) which will bring you 64y^3x^18/y^4.

4. Lastly, you cancel the y’s (Recall the formula “x^m/x^n=x^m-n.) to get the final answer 64x^18/y.

Hope this answers your question.