You need to find the amount of money you get each year, or 2.5% of $3200, and then multiply that by three because you put it in the bank for three years. To find 2.5% of $3200, multiply 2.5% by $3200 (of means x) and get $80. Multiply that by three and you'll get $240. But you still have the $3200 dollars you had before, so you would add that to the amount you got for interest and your total would be $3440.
