First find the square root
4x^-6= 2x^-3
9y^-4= 3y^-2
If a negative exponent is in the numerator, move the expression to the denominator and make the exponent positive
So instead of 2x^-3/3y^-2 make it
2y^2/3x^3
So
The answer will be 2y^2/3x^3
Hope this helps