conversations.from: human
conversations.value: A shady restaurant is charging customers gratuities after taxes without them being aware. If my total bill was $140, the sales tax in my city is 10%, I ordered a NY Striploin for $80, and I ordered a glass of wine for $10, how much did they charge me for gratuities?
  Give me a clear explanation.
conversations.from: assistant
conversations.value: The total bill before taxes or gratuities was $80 for the steak + $10 for the wine = $80+$10 = $90
  If the tax is 10%, then the taxes paid were $90 * 10% = $9
  That means that the total bill before gratuities was $90 + $9 = $99
  If the final bill was $140, then you were charged $140-$99 = $41 for gratuities