Stan took Lily to his friends restaurant on a date. The friend told the waiter to remove the $12 dessert from Stan's bill. Stan tipped the waiter 20 % which was a $15 tip. Fill in the blanks to write an equation that will determine the amount of the original bill,b.

The original bill, b, can be determined by adding the cost of the dessert, x, to the amount tipped to the waiter, t:

b = x + t

According to the given information, the cost of the dessert is $12 and the tip amount is $15:

b = $12 + $15

Now we can evaluate the expression to find the value of b:

b = $27