First find the number of quarts the hot tub holds by multiplying the number of gallons it holds by 4: 40 gallons * 4 quarts/gallon = <<40*4=160>>160 quarts
Then multiply the number of quarts of champagne Jackson buy by the normal price per bottle to find the cost before the discount: 160 quarts * $50/quart = $<<160*50=8000>>8000
Then multiply that number by 20% to find the amount of the discount: $8000 * .2 = $<<8000*.2=1600>>1600
Finally, subtract the discount from the total cost to find the final amount Jackson pays: $8000 - $1600 = $<<8000-1600=6400>>6400
#### 6400