Did the final replace a MT?

Yes. Probably.

The final exam is worth 120 points. Each MT is only worth 100 points. Therefore, the replacement of a low MT by a Final is on a percentage basis.

For example, your lowest MT = 55, your final = 90. You do not get a 90 for that low MT. Instead, you get (100*90/120 = 75). So a “75” replaces the “55”. Please double check your calculation of percentages – before you write to ask about this!