The first 8 years cost 8*10,000=$<<8*10000=80000>>80,000
The next 18-8=<<18-8=10>>10 years
They cost 10000*2=$<<10000*2=20000>>20,000 per year
So they cost 20,000*10=$<<20000*10=200000>>200,000
So the cost was 200,000+80,000=$<<200000+80000=280000>>280,000
Adding in the cost of tuition brings the cost to 250,000+280,000=$<<250000+280000=530000>>530,000
Since John pays for half the cost of raising the child, he pays $530000/2 = <<530000/2=265000>>265000
#### 265000