RÕ RÀNG NHÉ, NÓ BẢO
When the chocolates arrived in a heap with the bill, tips went up a miserly 3% compared to when no chocolate was given. But when the chocolates were dropped individually in front of each diner, tips went up 14%
vậy tại sao ? why ? rõ ràng nếu éo có bill thì tip giảm còn gì