Excel 2007 : Lower Range limit scores

Hello,
I know this may be easy but im having so much trouble with this question. The upper values are already set but i need to find the lowers one. I have no idea what to do. Any help would be great. I have been stuck on this 1 for hours. The upper range is 30,55,75,85,100. so how would i find the lower range. my teacher already put 0 in the first example.

Thank you.