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, b
Let b be the amount of the original bill.
The reduced bill will be b - 12 because the dessert was removed.
The tip will be 0.2(b - 12) because Stan tipped 20% on the reduced bill.
The equation is 0.2(b - 12) = 15. Answer: \boxed{b=90}.