Answer: The total cost is $874.86
Steps:
Start with determining the discounted price:
$1049 - discount 20% = 1049 - (0.2 * 1049) = 0.8*1049 = $839.2
At the checkout they will add the sales tax on this (discounted) price, the tax amount is worth 4.25%
tax = 839 * 0.0425 = $35.66
and that gets added to the total to pay:
$839.20 + $35.66 = $874.86