On average, drawing a smiley face on the check raises the tip od waitresses by 9% and lowers the tip of waiters by 3%.
12.
On average, drawing a smiley face on the check raises the tip od waitresses by 9% and lowers the tip of waiters by 3%.
On average, drawing a smiley face on the check raises the tip od waitresses by 9% and lowers the tip of waiters by 3%.