We know that Fashion Fun uses a mark-up of 285%. To determine the sell price in Sally's store we can use the rule of three.
Then, the sell price is
The sell price in Fashion Fun is 12.86.
The mark-up amount is the sell price minus the purchased price, then
Therefore the mark-up amoun is $8.36. Furthermore this is also the profit Sally will have if she sells the dress in this price.
If Sally doesn't sell the dress in this price she should make a discount in the price.