Question:
In January, the ratio of the number of butterflies to the number of bees in a garden was 7 : 3. In February, the butterfly population decreased by 20% while the bee population increased by 30%.
a) What was the percentage change in the combined butterfly and bee population?
b) If there were 168 butterflies left in February, what was the butterfly population in January?
Solution:
![P6 / Ai Tong / 2020 / SA2 Prelims / Paper 1 – Q20 [1 mark]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2021/08/P6_SA2_2020_Ai_Tong_Paper1_Q20-Qns.jpg?resize=400%2C260&ssl=1)
![P6 / Henry Park / 2019 / SA2 / Paper 2 – Q14 [5 marks]](https://i0.wp.com/sgprimaths.com/wp-content/uploads/2020/06/P6_Henry_Park_2019_Prelims_Paper2_Q14-Qns.jpg?resize=400%2C260&ssl=1)