To determine the amount of the original bill, we need to set up an equation using the given information.
Let's break down the information we have:
- The friend told the waiter to remove the $12 dessert from Stan's bill.
- Stan tipped the waiter 20% on the reduced bill, which was a $15 tip.
We can write the equation as follows:
Original bill - $12 (dessert) + 20% of the reduced bill (tip) = Total bill
Let's use variables to represent the unknowns:
b - $12 + 0.20b = Total bill
Simplifying the equation, we have:
0.20b - $12 = Total bill - b
Since we also know that the tip was $15, we can further simplify the equation:
0.20b - $12 = $15
Now we can solve for the original bill, b:
0.20b = $15 + $12
0.20b = $27
Finally, dividing both sides of the equation by 0.20, we find:
b = $27 / 0.20
Therefore, the original bill, b, is $135.