Answer:
The trader had paid [tex]5800[/tex] for the shirt.
Step-by-step explanation:
Price for which the shirt was sold [tex]= 0.87\times 8000\:=\:6960[/tex]
Let's say, the purchase price of the shirt for the trader was [tex]x[/tex].
[tex]1.2x = 6960\\\\x=5800[/tex]