We are given the following sets:
- \( B \) = Businessmen = 50,
- \( E \) = Engineers = 25,
- \( P \) = Parents = 2500.
We are also given the intersections:
- \( B \cap E = 0 \) (No businessmen are engineers),
- \( B \cap P = 25 \) (Businessmen who are parents),
- \( E \cap P = 15 \) (Engineers who are parents).
We are tasked with finding the total number of distinct individuals to contact, which corresponds to the union of the three sets:
\[
|B \cup E \cup P| = |B| + |E| + |P| - |B \cap E| - |B \cap P| - |E \cap P| + |B \cap E \cap P|.
\]
Since no businessmen are engineers, \( B \cap E = 0 \), and thus:
\[
|B \cup E \cup P| = 50 + 25 + 2500 - 0 - 25 - 15 + 0 = 2535.
\]
Thus, the total number of people to contact is \( 2535 \).