Alex has 3 baseballs.
He brings 2 baseballs to school.
What fraction of his baseballs does Alex bring to school?
The fraction will look like this:
Baseballs Alex takes to school/Total baseballs
n = Baseballs Alex takes to school
d = Total baseballs
n = 2
d = 3
2/3
Alex brings 2/3 of his baseballs to school!