Total number of students combined in robotics and science club = 75
Let there are x students in robotics club.
Let there are y students in science club.
So total students are 75

We are given that the science club has 9 more students than the robotics club.
So that gives us relation between x and y as :

Now plugging the value of x from equation (2) in equation (1) ,


subtracting 9 from 75,


dividing both sides by 2,
y = 33
So we have 33 students in science club .
Students in robotics club = 75 -33 = 42