#((4x^2y) / (3xy^2))^4#
#=> ((4 * color(red)(cancel(color(blue)(x))) * color(red)(x) * color(red)(cancel(color(blue)y)) )/ (3 * color(red)(cancel(color(blue)(x)) * color(red)(cancel(color(blue)(y))) * y)))^4#
#=> ((4x) / (3y))^4#
#=> (256x^4) / (81y^4)#