Answer:
50
Step-by-step explanation:
she starts with 9 plus the 10. so she has 19. Danny takes 4 so she has 15. then she trades so she gets 3 per marble she trades so it's like 15 times 3 which is 45. plus the 7 her parents gave her which is 52 and she gives 2 to her sister. so it's 50