Using a fishermans rib parrten to knit a brioche sweater

I used a fisherman’s rib knitting pattern to knit a Brioche sweater. It is a raglan and something wrong happened to the armhole decreasing and now the armhole is way too small. I did a decrease every 4 row because you have to decrease 2 stitches at a time but the pattern decreased every second row. How would i do the decrease to match up with the pattern.

I would use some basic calculations. Since you can measure your row gauge from what you have already knitted, you can easily determine how many rows you need for each arm. Then distribute the needed decreases evenly across those rows.

Welcome to the forum!
engblom has given you the method for calculating the frequency of your decreases over the length of the armhole. Working two decrease at each decrease row is a good way to go because it keeps the brioche pattern aligned. You need to take that into account

What is the name of your pattern and designer?

Thank-you. I find that my rows for brioche seem to be shorter when I knit Brioche as opposed to fisherman”s rib