Question:
The ratio of the number of marbles Ryan had to the number of marbles Audrey had at first was 2 : 7. After Ryan bought another 20 marbles and Audrey gave away 80 marbles, the ratio of the number of marbles Ryan had to the number of marbles Audrey had became 1 : 3. How many marbles did Audrey have at first?
Solution:
![P6 / Ai Tong / 2020 / SA2 Prelims / Paper 1 – Q16 [1 mark]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2021/08/P6_SA2_2020_Ai_Tong_Paper1_Q16-Qns.jpg?resize=400%2C142&ssl=1)