Question 377470
The marked price of the dress = D
the discount = 15% = 0.15
so the price after the discount = D -0.15 D = 0.85 D
the staff get additional 10% discount on this
so the reduction= 10% on 0.85 D = 0.1 *0.85D = 0.085 D
so the price for the staff after these two reductions = 0.85 D-0.085D = 0.765 D 

This is the final answer