How do i simplify (3xy to the power of -2) to the power of -2

Question

Please help i am so so confused and really don’t understand!

Answer 1

(3xy)^-2 = 1/9x^2y^2

(1/9x^2y^2)^-2 = (9x^2y^2)^2 = 81x^4y^4

-2 times -2 = 4

3^4 = 81, (xy)^4 = x^4y^4

answer is 81x^4y^4

Answer 2

(3xy)^-2 = 1/9x^2y^2

(1/9x^2y^2)^-2 = (9x^2y^2)^2 = 81x^4y^4

-2 times -2 = 4

3^4 = 81, (xy)^4 = x^4y^4

answer is 81x^4y^4