Problem Solving

In the figure above, two rectangles with the same dimensions overlap to form the shaded region. If each rectangle has perimeter 12 and the shaded region has perimeter 3, what is the total length of the heavy line segments?
(A) 15
(B) 18
(C) 21
(D) 22
(E) 23

OA: [spoiler](C)[/spoiler]

In the future, we're going to need the actual diagrams. There's no way that thing is official.

Anyway, judging from the question and the OA, the "Heavy Line Segments" consist of the overall perimeter of the entire figure, not counting those three line segments in the interior.

That makes this a simple problem: the total of all line segments in the figure is 24, and we have to subtract those three in the center. The question gives us that information being 3, and so 24 - 3 = 21. C.