Last week Besty made an 80 on her quiz. This week she made a 75. What is the percent of decrease in her score?

Iknow the answer but the calculator doesn't seem to give the right one

Can someone tell me if these are correct?

Ms. aniston asked seven students in her class to collect pet food cans for a local animal shelter. the dot plot shows the number of food cans collected by each student. each dot represents one student. what is the median of the data set? a. 6 b. 9 c. 7 d. 8