Over the last week, I've seen a version of the following brain teaser a bajillion times on Facebook and Twitter.

Despite the fact that it's gone viral several times before, people still can't seem to agree on an answer.
Say?
Some people see only four triangles.
@cecemoneey 4
Others see 10 or 12.
@cecemoneey 10
@cecemoneey 12
Still others see 19 or more.
@cecemoneey 19
There is, however, a definitive answer to the question of how many triangles are in the image.
