Don't know why I can't figure this out!!! Over or under estimate calculation...

Good day everyone... I'm trying to do a very simple calculation where I estimate a score for a resume and then assess an actual score during the interview. I want to show how accurate my estimate was versus the actual assessed value. The thing is, I want to show it as a string like "You underestimated their score by: x.xx%" or "You overestimated their score by x.xx%" and then color code them by how far off I was (perhaps red for <30%, yellow for 11-29% and green for 10% or less). This seems like it should be so simple, but I'm just not getting it right!!! Any help would be appreciated...

BigRic