Ceasar opens a bank account and makes an initial deposit of $800. the banker tells ceasar that he is going to receive an annual rate of 10% on his investment. find the bank balance assuming tom leaves the account untouched for 8 years.

As it was not mentioned, we assume that it is a simple interest rate (it would be different if it was compound interest rate)
 

So we have now:
- initial deposit of $800  (p=800)
- annual rate of 10%      (r=0.1)
- leaves the account untouched for 8 years  (t=8)

Apply the formula in the chart attached:



So the interest is 640$

Add this to the original deposit (800$) to get the full amount of money (the balance) after 8 years

800+640=1440$

Done!!

I hope that helps!