Carl, Jonson, Sally, and Emily will be taking a holiday trip together again. From their past experiences of traveling together, they know that it will not be easy to manage their expenses.

On previous trips, they had most meals together and shared many expenses as a group. However, sometimes one person or another wanted something special, in which case it was not fair to split the cost. They have learnt that it is neither good nor convenient to have only one person holding all the cash in foreign currencies to make payments. It is also impractical to share the expenses at each and every juncture.

They need to devise a simple way to record for each item what is spent, how much each person contributes (if any) to the payment, and how the expenses are shared among them. It will be assumed that the data can be entered at suitable times into an electronic spreadsheet. With the consolidated information at the end of the trip, each person will know how much he or she has spent on the trip and how much he or she owes the others.