To find the interior angle of any regular polygon you can use the formula

where n is the number of sides
So,

The measure of an interior angle in a regular octagon is 135
The range would be -1 to 8
16*12=months
16*365=days
Then take that answer and multiply it by 24 for hours then take that number and multiply it by 60 for minutes and then take that number and multiply it by 60 for seconds.
PQ // BC
then
Angle P = Angle B, A is common angle the two triangles are similar
AP/AB = AQ/AC
8/18 = 12/ AC
AC = 12 * 18/8 = 27 (your ans: D)
AQ + QC = AC
QC = AC - AQ = 27 - 12 = 15 (if it was required)
tan60 = y/8
y = s tan60 = 8sqrt(3) (B)
Next time, post each question separately.