A convex pentagon has interior angles with measures $x+1$, $2x$, $3x$, $4x$, and $5x-1$ degrees. What is the measure of the largest angle?
I REALLY suggest you look back and see what the other guy said about the sum of the interior angles of a polygon. You can do this problem by yourself and you shouldn't even need help.
But hey, cheer up! I used to be in the same boat as you, thinking I was never going to get good at geometry. But as I did more problems and did more practice, I can say that I am thinking slightly less that I am never going to get good at geometry. Woohoo.