How will I calculate this question, and what is the relationship between the numbers in the example

Me. i can't figure out this question. give an explanation too. .

Pepe and leo deposits money into their savings account at the end of the month the table shows the account balances. if there pattern of savings continue and neither earns interest nor withdraw any of the money , how will the balance compare after a very long time ?

Which equation is represented by the graph below?