Ok, so first we need to find what 3/5, an hour is. So multiply 60 by 3/5. You should get 36. Now, the remaining time is 24 minutes. She spent 3/8 of 24 minutes brushing her teeth and putting her pajamas on. To find 3/8 of 24, you multiply 24 and 3/8. You should get 9. So now we combine those times together and we get 45 minutes. So to find the amount of time remaining (in which she read) you subtract 60 and 45.
So Jenny spent 15 minutes reading a book.
