How to Decrease Armhole In Crochet

How to work in an easy way an armhole and our fashion garments remain always perfect?

In this example the decrease is for a size 42 woman and is performed with decreases at the beginning and end as follows:

If the thread or yarn is semi thickness: decrease 3 split stitches, 1 simple crochet and then continues normally weaving in fantasy stitch.

If the material is of average thickness: decrease 4 split stitches, 1 simple crochet and then continues normally weaving in fantasy stitch.

If the material is thin thickness: decrease 5 slip stitches, 1 simple crochet and then continues normally weaving in fantasy stitch.

Then continue weaving straight up to the shoulder height.