If the dinner altogether costs £64, and there is a 20% tip, that brings the total amount paid to £76.80, and if four people are paying £19 towards the total, then there would not be enough for them to pay for both the meal and the tip, as 19x4 is 76, and the total is £76.80, meaning you need another 80 Pence.
Answer: No, as there is 80 pence off the total amount with all of there money added together which they would need to pay for the meal and the tip.