To determine how much change Robert receives after buying a candy bar for 78 cents with a one dollar bill, we first need to convert everything into the same unit, which is cents. One dollar is equal to 100 cents.
Now, we simply subtract the cost of the candy bar from the total amount paid:
100 cents (one dollar) – 78 cents (cost of candy bar) = 22 cents
This means that Robert will receive 22 cents as change from his purchase.