If Pamela ranks seventeenth in a class of thirty-one, what is her rank from the last?

The formula relating ranks from the start and end with total number of students is:
$$\text{Total Number of Students}=\text{Rank from top}+\text{Rank from bottom}-1$$

Given:

* Total = $31$
* Rank from top = $17$

Substitute values into the formula:

$$31=17+\text{Rank from bottom}-1$$

$$31=16+\text{Rank from bottom}$$

$$\text{Rank from bottom}=31-16=15$$

Pamela's rank from the last is $15$.