1/2 + 2/5 i need someone to explain this, cause i'm extremely stupid

Don't worry hun you're not stupid. so basically the purple pen means the obvious right? it means that those are the numbers that you will be focusing on first. you are going to make sure that you change them to the same bottom # that way you are able to add them at the very end okay? so what we are going to do is find a # that those bottom #s both go into right? and that would be ten. So what you want to do is multiple top and bottom by the same number to get the denominator to 10. (as pictured) then you will bring both equations down for clean space and add them. like this: