Montgomery deposited $319.25 in a savings account that earns 2.6% simple interest. What is Montgomery's account balance after 14 years?

After one year he will have

319.25*1.026

on his bank account

Next year we have to multiply new value again with 1.026 to get new value.

that means that after 14 years he will have:

319.25*1.026^14 = $457.29

If however 2.6% is for his starting money each year than his balance after 14 years will be:

319.25 + (319.25*14*0.026) = 435.46

That would be $435.46.