Problem: You do not have an attached picture. Though, I can help you out with this question.
So, three-fifths of the members are girls. There are 30 of girls. We can immediately make an equation using "x".
3/5x=30
3/5x × 5/3=30 × 5/3
x=50
Thus, there are 50 members in total. Though if x is too hard for you, you may substitute it by using another variable.
Variable in here is x.