Steve's barking; NYC Schools 7 Students Pay a teachers salary

In New York City we pay our teachers less then 1/3 the money that our students generate for being in the classroom.
The Union contracts call for 22 students in a class and we all,know that max and perhaps then some are registered in the class
The numbers tell us that each student generates $20,000.
Let's go for the high number and say that we have in each class room a teacher that makes $100,000 dollars with a 40% fringe benefit equalling $140,000 dollars, bingo 7 students in the classroom pays
for the teacher.
 Now using that $20,000 number we need to pay the principle and the principles staff. Now that may not seem like a lot of money but because it's multiplied  by the number of classes in the school., We'll go under the assumption that one student in the class helps pay the principle and staff. The same being true for heat, light, toilet and cleaning supplies. One student in every class helps pay for this.
The custodial staff will draft another student multiplyed by the number of classes.
Now we have to pay for transportation, for argument sake we'll,say another student from this mythical class pays for that. Now what about supplies, we'll be really generous with that money and say a half a student pays for that, making that $10,000 per class for supplies, chalk, paper, pencils, and perhaps a computer.
Now let's add this up, 7 students in a class pays for the teacher. 1 student principle and staff, 2 students custodial staff and cleaning provisions. 1 student for transportation and 1/2 student for classroom supplies. That equals in dollars $230,000. Now the students in the class generates $440,000, what magic was created to make $210,000 disappear?

(1) Most teachers don't make $100,000 a year.
(2) The $20,000 a year per student is an average including special Ed. ( That's another question, does special Ed retard the development of those that it reportedly is trying to help?)