Number of shirts a department store bought = 200
Cost price of 200 shirts = $5400
Cost price of 1 shirt :


Thus, the cost price of one shirt = $27
Price at which the department store sold each shirt = $30
Which means :
▪︎Cost price of shirt = $27
▪︎Selling price of shrit = $30
Since selling price is greater than cost price, there was a markup in the price of the shirts.
We know that :

Markup percentage in the price of the shirts :





Thus, the percentage of markup = 
Therefore, the percentage of markup in the shirt's price = 