5 to the power of -3 in exponential form

What could explain what happened when the time was equal to 120 minutes

Given the sequence 7, 14, 28, 56, which expression shown would give the tenth term? a. 7^10 b. 7·2^10 c. 7·2^9

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 ?