Write final_grade(scores, weights): one final grade from several scores, where some count more than others. The weights can be any positive amounts: percents like 20, 30, 50, or parts like 2, 3, 5.
| homework | midterm | final |
|---|---|---|
| 80 | 90 | 70 |
| homework | midterm | final |
|---|---|---|
| 20 | 30 | 50 |