Answer:
20%
Explanation:
In the graph, there is a cycle of increasing and decreasing. First, the original circle increases by 25% into the new, larger circle. Then, the circle does back to its original size. So, to solve we can assign a value to the smaller circle, increase it by 25%, and then find what percentage brings this back to the original value.
It is easiest to assign the value of 100 because it is easy to work with. So, let's say the smaller circle is 100; this increased by 25% is 125. The next step is to find what percentage of 125 brings us back to 100. There are multiple ways to do this such as guess and check or proportions/fractions. Either way, the correct percentage is 20%. If you decrease 125 by 20% you get the correct value of 100. This means that the missing number must be 20%.