Concept:
We are given a determinant condition. Such determinants are simplified by applying row or column operations and then comparing the resulting condition.
Step 1: Write the determinant condition.
\[
\left|\begin{matrix}
p& q-b& r-c\\
p-a& q& r-c\\
p-a& q-b& r
\end{matrix}\right|=0
\]
The determinant being zero means the rows or columns are linearly dependent.
Step 2: Use the known result for this determinant form.
For this standard determinant form, after simplification, the condition becomes
\[
\frac{p}{a}+\frac{q}{b}+\frac{r}{c}=2
\]
Step 3: Final answer.
\[
\boxed{2}
\]