This is one of those "brain teasers" that often pop up on Facebook with an annoying and statistically ambiguous title like "Only 5% of the population know the answer to this puzzle!" According to The Daily Mail, this one has been floating around since December.
For once the people in the comments actually have something worth arguing about. You may not have noticed at first but the illustrations in the last equation are different than all the other ones. Let's walk through it.
First, apples definitely equal 10, that much is clear. From the next equation you can guess that each banana bunch equals four. Now we can assume that the coconuts equal two.
So the last equation should add up to 16. 2+10+4 =16 right?
BUT there's only ONE coconut half this time and only three bananas. So is that 1+10+3=14?
This has people arguing about whether the concept of the fruit is a constant number or if that number can change as the picture of the fruit changes. To make matters worse, Dr Kevin Bowman, a Mathmatics course leader at University of Central Lancashire spoke to the Daily Mail to try to "clear" things up. According to him, they can represent whatever you want since the only unambiguous fruit is the apple. Also, everything you thought about coconuts is wrong. He concluded his interview with this:
You might even say that the two coconut pieces in the third equation are different sizes, and therefore add up to three quarters or even seven eighths when put together.
In that sense, there are an infinite amount of possible answers.
So no one can know the real answer until, somehow, the commenters on Facebook reach some sort of philosophical consensus on how we treat visual representations of fruit.