[16x^5y^10/81xy^2)^3/4

To simplify the expression (16x^5y^10/81xy^2)^(3/4), we can follow these steps:

Step 1: Rewrite the expression using the properties of exponents:
- (16/81)^(3/4) * (x^5/x)^(3/4) * (y^10/y^2)^(3/4)

Step 2: Simplify each term within the parentheses:
- (2^4/3^4)^(3/4) * (x^(5-1))^(3/4) * (y^(10-2))^(3/4)

Step 3: Further simplify each term:
- (2/3)^(3/4) * (x^4)^(3/4) * (y^8)^(3/4)

Step 4: Apply the power of a power rule to each term:
- (2/3)^(3/4) * x^(4 * 3/4) * y^(8 * 3/4)

Step 5: Simplify the exponents:
- (2/3)^(3/4) * x^3 * y^6

So, the simplified expression is (2/3)^(3/4) * x^3 * y^6.