This is trying to tells us what is 54.20-9.99. So first I'm going to add .01 to 9.99 to make 10. We do this because we need to keep the distance between these two numbers the same. Since I done added .01 to 9.99, I have to add .01 to 54.21. So now this leaves us with a new question to answer. 54.21-10=44.21. As you can see this is a very easy strategy to learn and is good.