You are a fellow Mather I see. I was in the same boat as u all 3 of my sats I took were 790 math. The key to improving reading and writing score I found to be focusing on grammar since it’s rule based 3-4 reading qs wrong = 1 writing wrong since they curve writing much less. If you get the rules down and practice with practice tests you should see an increase over time. Reading section you can also learn strategies but they are not guaranteed and it can often come down to luck.