I started Genetics a couple of weeks ago and it is like a bajillion times harder than Honors Genetics Bio. I would appreciate if someone could clarify somethings and help give me an explanation on how the addition and multiplication rule works. Furthermore, my teacher says that during the AP test there won't be time for me to make a punnet square so I need to know how to find the amount of phenotype and/or genotype without making a punnet square. I can do the little ones like if it's Bs x Bs and B=Black hair theres going to be a 3/4 chance that the offspring receiving Black hair. I also know that codominance follow the ratio 1:2:1. But what can I do if it was a larger punnet square like AABBCCDDEE x aabbccddee? If it was a problem like BbSs x BbSS and we needed to find the number of offspring of F2 generation with a certain trait, my teacher would go something like (3/4) x (1/4) and get (3/16). How does he know that that certain trait is gonna produce 3/4 of the trait and other 1/4. Is there a pattern within the number of each punnet square or is it just something one has to remember?