I think that percent is easy. Everyone can do it. Yesterday I practice percent in Khan Academy.
I think that decimals are easy too, but I don't know that everyone can do it or not. Yesterday I also practice decimals in Khan Academy.
I think that word problems are medium-hard. I practiced Khan Academy yesterday and I didn't understand. I'm confused because Khan Academy's word problems are hard. I think that some student can do it. Not every student, but Mr. Gary's word problem test is easy. :)