If John and 3 friends ordered pizza for $13.00 and they paid $13.20 where in they also used the $6.00 gift certificate. Then we can deduce that the total amount of the bill was $13.20 + the gift certificate which is $6.00 which is equal to $19.20 and since the pizza was for $13.00 then we can deduct this from the total bill to get the amount of the drinks, ergo $19.20 - $13.00 = $6.20 since there were 4 large drinks so we divide the total amount of the drinks to the number of drinks. We would have $6.20 / 4 = $1.55 / large drink.
So the answer would be:
B. 4d + $13.00 – $6.00 = $13.20:$1.55