The answer is 19.
I know the OP said not to explain, but I will explain my answer. The first line is correct, but not relevant. The other two lines are incorrect and still not relevant. The last line is the only one looking for an answer to the the equation which is 19.
What you stated is somewhat correct.
What we are given in the example is a 'mathematical sequence'. Whether the numbers actually are added correctly, in the base 10 system that we normally use, is irrelevant.
The example is asking for an answer to the sequence, as given.
I understand the natural tendency to answer it in sequence, but I don't see where it is directed to answer it in sequence. The other information in the picture could also be simple obfuscation to get you to answer it in sequence. Sometimes the simplest answer is the best.
I reserve the right to be wrong.
Your right, nowhere does it say to figure out the sequence. However, hl nyuf, xgufpsu sequencing, there is no order. So what makes you think that 8+11=19. Because of the base 10 sequence we've been taught. My point is, there is a sequence in the example, and because it is a mathematical sequence, to solve it, you should consider the sequence.
and, like I said before, 'I reckon I'm a dummy'.
