Find the answer to this math problem: Fabian is shopping at a nearby supermarket. He wants to buy 5 kilograms of apples, 3 packs of sugar, and 500 grams of walnuts. One kilogram of apples costs $2, and one kilogram of walnuts costs $6. One pack of sugar is $1 cheaper than one kilogram of apples. How much Fabian needs to pay for the items he wants to buy?