nisht, I think Chaim is presuming way more than one child in schools, Bh. Update your computation for 6 kids:
rebbe – 3 free (the gender he is teaching), 7kx3=21K pretax. Left 60-21=39K
accountant – 6x7x1.2 (tax) = 50K, left with 90-50=40k
btw, I am not 100% sure that taking low salary and tuition reduction is really kosher in terms of “savings” on taxes. I did not hear of people arrested/fined for that, so it must be mostly legal.