Question 9
The bar chart shows a company’s notebook sales by year. In each of 2018 and 2019, sales increased by $60\%$ compared with the previous year. In each of 2020 and 2021, sales decreased by $25\%$ compared with the previous year. Sales in 2021 exceeded those in 2017 by $30800$ notebooks. How many notebooks were sold in 2021?
