Answer:
A merchant allows a 20% discount
price after reduction 33,500*0.8=$26800
decrease 20% =1-(120/100)=08
the merchant always makes a 10% profit on this item
10% (increase) coefficient of 1.10
initial cost price: 26800/1.1=$24363.63636
tps = increase of 12% = coefficient 1+(12/100)= 1.12
sales price GST included: $24,363.63636*1.12=27287.27272=$27287.28