11
11
11.
that does not make any sense
The answer is 15 because the pattern is subtract one, add two
9, 10, 11 and 12
11, -10, 9
15
The counting sequence is making increments of 11,that is, the n-th term will = 11 x nn = 12,t = 12 x 11= 132
The next figure would be 21, followed by 11 & 10.
4 5 6 7 8 9 10 11 12 13
A "calculation error".