The following table shows the number of units of a product manufactured and sold by a company in 5 years. Calculate the total number of unsold products.
| Years | Number of units manufactured (in hundred) | Sold (in hundred) |
| 2018 | 440 | 350 |
| 2019 | 500 | 450 |
| 2020 | 320 | 300 |
| 2021 | 450 | 400 |
| 2022 | 290 | 200 |
1
30,000
2
40,000
3
50,000
4
20,000