You have to turn the percent into a decimal to do the math.
80 .40 = 32 (That's the discount.) Now we subtract the orginal price from this.
80 - 32 = 48
Now we need to find the tax value.
48 (our new price) .0675 = $3.24
Add this back onto the price to get our final price.
3.24 + 48 = $51.24