Answer: See explanation
Step-by-step explanation:
• Gilberto can easily determine that the whole sandwich, while twice as long as the half, is priced at less than twice as much. = Unit of account.
In this case, the sandwich has been valued in terms of money. Therefore, the role played here is the unit of account.
• Gilberto accumulates money in his savings account for future purchases. = Store of value.
The role played by money here is the store of value. This is when money is stored so that it'll be used for future purposes or to generate further wealth.
• Gilberto buys his lunch with a $10 bill = Medium of exchange.
Money plays the role of a medium of exchange here since Gilberto used it in exchange for the food that was bought.