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?
The total bill before taxes or gratuities was $80 for the steak + $10 for the wine = $80+$10 = $
<gadget id="calculator">80+10</gadget>
<output>90</output>
90.
If the tax is 10%, then the taxes paid were $90 * 10% = $
<gadget id="calculator">90*10*.01</gadget>
<output>9</output>
9.
That means that the total bill before gratuities was $90 + $9 = $
<gadget id="calculator">90+9</gadget>
<output>99</output>
99.
If the final bill was $140, then you were charged $140-$99 = $
<gadget id="calculator">140-99</gadget>
<output>41</output>
41 for gratuities.

<result>41</result>