My price includes depends on the amount of the items
The basic rate is $60, including 5 free tests
If the amount is less than 50, each extra test will be $4.
If the amount is less than 100 but more than 50, each extra test will be $3.5.
If the amount is more than 100, each extra test will be $3.
Simplify, you can follow the table below (N is the total number of test)
| Number of tests (N) | Price |
| 1-5 | 60 |
| 6-50 | 40+4N |
| 51-100 | 42.5+3.5N |
| >100 | 45+3N |
