Input tax credit

Before 12%, 20,30 profits
A cost 100 sp (120+14.4)134.4 A pays 14.4 tax to gov   
B cost 134.4 sp (150+18)168 B pays 18 tax to gov, B gets 14.4 from gov 
C(final consumer): cost 168 

After 5%, 20,30 profits
A cost 100 sp (120+6)126 A pays 6 tax to gov   
B cost 126 sp (156+7.8)163.8 B pays 7.8 tax to gov 
C(final consumer): cost 163.8

Before 8%, 20,30 profits
A cost 100 sp (120+9.6)129.6 A pays 9.6 tax to gov   
B cost 129.6 sp (150+12)162 B pays 12 tax to gov, B gets 9.6 from gov 
C(final consumer): cost 162 

After 1%, 20,30 profits
A cost 100 sp(120+1.2)121.2 A pays 1.2 tax to gov   
B cost 121.2 sp(151.2+1.512)152.712 B pays 1.512 tax to gov 
C(final consumer): cost 152.712