Hello

I am trying to understand how many stitches I need to decrease by and on which rows exactly but I don’t understand the pattern which says:

When work measures 4cm decrease on each side, 2 sts in from edge as follows:

1 st 7 times every 6 rows, 1 st 6 times every 4 rows.

Please could someone explain this. How many stitches are decreased on each row?

Thanks!