I don't know how to figure..24 girls at the picnic..2/5 at picnic were boys. How many students at picnic?
If 2/5 were boys then 3/5 were girls
so
3/5 * number of students = 24
or number of students = 24 * 5/3
another way - proportions
3/5 = 24/number of students
3*number = 24*5
number = 24*5/3
which is 8*5 by the way