Answer: 
A,B,D
Step-by-step explanation:
case A) If the price is marked down by  percent, the new price will be 
we know that
If the price is marked down by 10  percent
then the new price will be
10%= 10/100=0.10
(1 - 0.10) *$28= 0.90 * $28
=$25.20
therefore The statement case A) is True
case B) If the price is marked down by 25 percent, the new price will be $21
we know that
If the price is marked down by 25 percent
then the new price will be
25%=25/100=0.25
(1-0.25)* $28=0.75*$28
=$21
therefore The statement case B) is True
case C) If the price is marked down by 50 percent, the new price will be $19 we know that
If the price is marked down by 50 percent
then the new price will be
50%=50/100=0.50
(1-0.50)*$28= 0.50*$28
=14 
therefore The statement case C) is False
case D) If the price is marked down by  35 percent, the new price will be $18.20
we know that
If the price is marked down by 35 percent
then the new price will be
35%= 35/100=0.35
(1-0.35)* $28=0.65*$28
=18.20
therefore The statement case D) is True
case E) If the price is marked down by 40 percent, the new price will be $29.80 we know that
If the price is marked down by 40 percent
then the new price will be
40%=40/100=0.40
(1-0.40)*$28= 0.60*$28
=$16.80
therefore The statement case E) is False