This is because you see that 12 is 1/2 of 24 and if you do 13x2 you get 26$ so for the 12 pack if you double it you will be paying 2$ more than if you got the OG 24 pack
Answer: You would divide the rectangle into half, to form two congruent triangles. When you multiply the area of 1 of the triangles, it gives you the area of both triangles, and so the area of the triangle as a whole.