HELP please! have no idea how to do this

Answer:
315/575
Step-by-step explanation:
The total number of books that are over 10
110+ 150+ 255+60 =575
The total number of childrens book over 10
255+60 =315
P ( childrens given that it is greater than 15)
= childrens over 10 / books over ten
= 315/575