Stan took Lily to his friend’s restaurant on a date. 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. Fill in the blanks to write an equation that will determine the amount of the original bill,

Let x be the amount of the original bill.

After the dessert was removed, the reduced bill was x - 12.

Stan tipped the waiter 20% on the reduced bill, which is 0.2(x - 12).

Therefore, the equation is: x - 12 + 0.2(x - 12) = x - 12 + 0.2x - 2.4 = x - 2.4 + 0.2x = 15.

Let's assume the original bill amount as "x". Since Stan tipped the waiter 20% on the reduced bill, the reduced bill amount will be x - 12.

According to the question, the tip amount is $15. So, the equation can be written as:

0.20 * (x - 12) = 15

Simplifying the equation:

0.20x - 2.40 = 15

Finally, rearranging the equation:

0.20x = 17.40

The equation that will determine the amount of the original bill is 0.20x = 17.40

Let's start by defining the variables that we need to solve the equation:

- x: the original bill amount
- y: the reduced bill amount after removing the dessert
- z: the original dessert cost

We know that the friend told the waiter to remove the $12 dessert from Stan's bill, so the equation would be:

y = x - z

Next, we are given that Stan tipped the waiter 20% on the reduced bill, which was a $15 tip. This means that the reduced bill amount (y) plus the tip (15) should equal the original bill amount (x):

y + 15 = x

Now, substituting the value of y from the first equation into the second equation, we have:

(x - z) + 15 = x

Expanding the equation, we have:

x - z + 15 = x

To find the value of the original bill (x), we need to isolate x on one side of the equation. We can do this by moving the terms without x to the other side:

- z + 15 = 0

Now, let's isolate z:

- z = -15

Multiply both sides of the equation by -1 to solve for z:

z = 15

Therefore, the original bill amount (x) can be calculated as:

x = z - 15
x = 15 - 15
x = 0

The original bill amount is $0.