Hello
The stitches add up, they are just rather confusing to decipher.
On row 3 there is a dec near beginning of row and one near end of row. One is the raglan shaping for the arm and one is the neck shaping.
The raglan then dec on every alternate row so row 5,7,9,11,13, 15, 17 and so on
The neck shaping though decrease on alternate rows only twice more, rows, 5 and 7
And then it is only decreased on the 4th row 11, 15, 19, 23, 25 (these are the 5 times)
In effect you dec both ends for a couple of alt rows but then you have a pattern of
Dec at raglan
Dec at raglan and neck
Dec at raglan
Dec at ragkan and neck
And so on. Because the raglan is every 2 rows and the neck every 4th.
When you have done the neck the correct number of times it will be down to 11 stitches. Then you have a few more raglan edges to continue to dec down to 7.
I hope this helps. These patterns are hard to understand but it becomes easier.