Answer:
and $475 deposited into the account on her birthdays by her 18th birthday.
Step-by-step explanation:
It is given that, on Gabriela’s first birthday, her parents gave her a $50 savings account.
Initial term : 
On every birthday after that her parents added to the account, increasing the amount they deposited by $25 each year.
Common difference : 
It forms an AP: 50,75,100,...
nth term of an AP is

Substitute
and
in the above formula.

It represents the amount deposited into the account after n birthdays.
We need to find the amount by her 18th birthday.
Put n=18 in the above equation.




Therefore, $475 deposited into the account on her birthdays by her 18th birthday.