Hello!
[tex]\large\boxed{\frac{4}{15}}[/tex]
Since she is splitting it equally with 3 people, we will need to divide the amount brought by 3.
Dividing by 3 is the same as multiplying by 1/3, so:
[tex]\frac{4}{5} * \frac{1}{3} = \frac{4*1}{3*5} = \frac{4}{15}[/tex]
Therefore, each friend receives 4/15 of a cake.
