All distributive property not multiplication

:24% of students in a class are girls. if there are less than 30 students in this class, how many students are there? how many girls are there?

Can someone factor this fully? my friend and i have two different answers and i would like to know if either of them is right. you in advance. a^2 - b^2 + 25 + 10a

There are a total of 75 students in the robotics club and science club. the science club has 9 more students than the robotics club. how many students are in the science club?