This means that 12 cars are green,12 cars are blue,and 12 cars are yellow/white. which means there are 4 groups of cars which all together equals 48 which is 48 divided by 12 equals 4 or just do 12 +12+12+12+48 or
4+4+4+4+4+4+4+4+4+4+4+4=48
Meaning there are 4 groups and 12 is 1 part of them which makes 1/4