Sales including sales tax 25500 lets say good value is X then sale tax at of 17.5% will x*(17.5/100 ) + x = 25500 1.75x=25500 Sales Value = X + 21702 so 21702 + 21702 * 17.5% = 25500
on purchase we get sales tax refund from so net sale tax figure will be 21702-18100=3602 the sale tax paid to the authoties 3602*17.5% 630.35