If the first ounce is already $0.22, then we have to calculate how much it cost for the remaining ounce.

The remaining ounce is 1.8 oz. If each additional ounce or fraction of an ounce weighs $.17 then, 1 more ounce cost $.17 and the remaining 0.8 oz cost $.17 too.
Hence, the total cost to mail a first-class letter weighing 2.8 oz is:

The total cost is $0.56. (Option A)