A secondary source in when you don't get the information from the person who said let's say you asked what's for lunch today and they told someone to tell you fried chicken but they told you chicken sandwich the answer can change before it gets to you.
I don't want to be rude or anything but this looks like it would be a math question
You could either 1. discuss with the teacher(s) on how poorly he treats the classmates and try to find a way to get him to stop
or
You could try and talk to said bully about how is making the class feel with how he has been treating them