In marlas school 6/15 of the students do not ride the bus to school. of these students 5/9 walk to school. what fraction of the students in marlas school walk to school? explain

For the answer to the question above asking what fraction of the students in marlas school walk to school? 
Fraction of the students in Marlas school walk to school=5/9 of 6/15

Fraction=(5/9)*(6/15)=(5*6) / (9*15)=30/135=2/9

 2/9 of the studens in Marlas school walk to school.