Question 192472
x^(-2y^4)  /  (4y(-3))^2

1/x^(2y^4)  /  (16y^-6)

1/x^(2y^4)  /  16/y^6

1/x^(2y^4)  *  y^6/16

y^6/(16x^(2y^4))

check,  let  x=2,  y=1  arbitrarily

check  initial  expression

2^(-2)/4^2=1/64

checking  final  expression

1/(16*2^2)=1/64    ok