There are 4! ways in which she can hang the bulbs, which means 4x3x2x1. this is 24 ways.
g o b p
g o p b
g b p o
g b o p
g p o b
g p b o
o g b p
o g p b
o p g b
o p b g
o b p g
o b g p
b o g p
b o p g
b p o g
b p g o
b g o p
b g p o
p g o b
p g b o
p b o g
p b g o
p o b g
p o g b
of these ways, there are 12 where green and brown aren't next to each other
