Final answer:
An explicit rule for the student's savings account with a starting deposit of $400 and additional monthly deposits of $25 is M = 400 + 25n. After 12 months, the account will have $700.
Step-by-step explanation:
To write an explicit rule representing the amount of money deposited into a savings account, we consider the initial deposit and the regular monthly deposits. In this case, the initial deposit is $400, and there is an additional deposit of $25 each month. The explicit rule can be defined as M = 400 + 25n, where M represents the total amount of money in the account after n months.
To calculate the total money in the account on month 12:
Plug 12 into the explicit rule for n: M = 400 + 25(12).
Calculate the total: M = 400 + 300 = 700.
Therefore, at month 12, you will have $700 in the savings account.