His taxable income is 100,000-30,000=$<<100000-30000=70000>>70,000
So he pays 20,000*.1=$<<20000*.1=2000>>2000 tax at the lower rate
He has to pay 70,000-20,000=$<<70000-20000=50000>>50,000 at the higher rate
The taxes for that is 50,000*.2=$<<50000*.2=10000>>10,000
So his total tax bill is 10,000+2,000=$<<10000+2000=12000>>12,000
#### 12000