The image below is made up by these 4 different things as you can see. The answer consists of 5 characters.
What does it represent?
Hint(related to image 1)
A number, a triangle, a polygon
Hint2(related to one of the remaining 3 images)
D, I, L etc...
Hint3(related to image 4)
A letter and a number
Hint4(related to image 1 again, since this one probably is the hardest one)
grey(nr), yellow, yellow