Explanation: We can start by finding the amount that they should tip. The total bill is $78, so we should take 15% of 78 and add it to the total. 0.15 * 78 = 11.7 78 + 11.7 = 89.7 This means that the total cost of the bill, with a tip, is $89.70. Since there are 4 people, we have to split this total into 4 if they all want to pay equally. 89.70 / 4 = 22.425 = $22.43 !
