19.1 should be your answer
The first figure has 3 angles, the second one has 4 angles, the third one has 5 angles so the next one will have 6 angles.
The violet figures inside stick with each side of the outer figures in the middle, so the last figure will look more less like in the attachment.
I believe the answer to this is:
Mean: <u>8.7</u> minutes
Median: <u>9</u> minutes
Hope this helps! :D
Negative since the answer would be -13