Once you reach calculus, you will learn a easier way to solve this problem. You can also use a formula or TSI calculator to find it. If you don’t have either of these available, I will explain step by ste how to solve this problem on paper. You have to be able to find 7% of $320 billion. To do this, you can multiply 320 by .07. Ignore the units for now. So if you multiply 320 by .07, you should get 22.4. So 7% of $320 billion is $22.4 billion. According to the problem, the increased rate will always be 7%. There are 11 years between 2004 and 2015. Let’s find the amount of 2005 first. You would find this by taking the original $320 billion and add the 7% to it because that is how much it will increase by. Because it is increasing, you must add the 7% to the original 100%, the $320 billion. $320 plus $22.4 is $342.4 billion. This was the amount spent in 2015. Next, you would find 7% of $342.4 billion, which would be 342.4 multiplied by .07. Take the answer and add it to $342.4 billion. Continue doing this until you reach the amount spent in 2015. Hope this helps!