1600/.80=$2000 original cost

54

1900

8000

X/1600 = -(20/100) x/16 = -20 x = -320 so subtract 320 from the given options and see which gives you the value 1600 i.e add 1600 + 320 = 1920 so the answer is 1600 is 20% discount of 1920 !!