Pam and her friends have 802% left of cookies. Before she started she had 1000% of cookies. How much % did Pam and her friends use.

When you write "1000 %", the question is, what is it a percent of? a percent has to be of something. I will assume here that the "what of" is a certain amount of measurement (let's say the number of cookies that is good to use on a given day"

anyway, so they started of with 1000% of this measure. afterwards, they were left with 802%.

How much they used is the difference between the two: 1000%-802%, which is 198 %

so that's how they must have used, 198 of this certain amount.