Statistical techniques

It depends the wording of the question. The trend is not necessarily exactly linear, in which case the 'trend line' will be the line that most nearly goes through the trend points.

so basically when I find the trend and if ts around the middle of two items, i have to find the average once again. that will the trend line is that right

No - that will be the trend. The trend line is the line that most nearly goes through the trend points.