Okay, so starting with the first image, I looked at what the total was for that row all together and halved it. I then halved it into quarters as there are four numbers. The symbols are not both 7 so I lowered one number by 1 and I added 1 on the other number, creating 8 and 6. Those numbers together were able to make 28 but I didn't know which number was which, so I looked at the second row on the first image.
There was only 1 triangle symbol and there were 3 squares, so I used three 6's and one 8, but that only created 26 and the answer was 30, so I tried it the other way round, doing three 8's and only one 6, which got the answer I wanted.
The next image had one triangle symbol, one square symbol and two circle symbols. Knowing what the triangle and square would equal (14), I just counted the numbers from 14 to 22 (which was 8) and halved it because there were two circles. I then had my answer for circles.
I found image 4 irrelevant so I went to the next image, and I had the find out what the hexagon symbol represents.
There were 2 circles and 1 triangle in one row and 2 circles and one square in the other, which is the one i did first, I combined the circles together so I had an 8 and the square was worth 8 too, so I added those numbers together and got 16, the total for the row was 23, so once again, I counted up until I got the total.
The number for the hexagon symbol was 7, I finally had the answers to solve the mystery column.
I added the two circles, the one square and the hexagon (4+4+6+7) and the answer was...
...21!