Nine ladies from the sewing circle went out to a restaurant to celebrate completing a quilt. The total bill came to $166.11 of which $15.00 was tax. They decided to leave an 18% tip. How much of a tip should they leave the waitress? In addition, each of the ladies will contribute the same amount towards the tip so how much will each lady have to contribute to the tip?

Some professions that provide you with personalized service don't pay well and so they expect a tip - waiters and waitresses, cab drivers, tour guides, hotel bell hops (yes they do still exist in many places), hotel maids, valet attendants (they park your car for you), movers and barbers and hair dressers.  
Often, tips are based on percentages.