The one year-plan would have a credit, so it would have a positive sign. In the monthly plan, there is a high risk of being late in paying the bills. That's why a fine of $10 is given for every month that you are late. If you are not time conscious and you end up being late every month, it would give you a negative balance.
(1) Repetition allowed : There are 4 choices for both positions, so 4 × 4 = 16 2-digit numbers can be formed. (2) Repetition not allowed : There are 4 options for tens position, and three options for ones position. Therefore, 4 × 3 = 12 2-digit numbers can be formed.
