The tip is a economic reward that is given as thanks for a good service and for the product consumed.
In most places, the client decides whether or not to give a tip and the amount of the tip. In the United States, the custom of tipping has expanded beyond restaurants. Generally, 15% of the value spent is left as a tip for the person providing the service, be it a waiter, taxi driver, or any other activity in which the tip is usual.
273 dollars for 13 hours of work is a unit rate of 273/13=21 dollars per hour. Multiplying this by 8 hours of work, you get 168 dollars. Hope this helps!
