x ? 2 = 16; 14, 18, 21, or 12 what is the solution?

You're going to have to explain this a bit better.

Are you asking, "x (what operation) 2 = 16; 14, 18, 21, or 12?"

Regaurdless of the operation, we need to know what x is to solve this...

x – 2 = 16; 14, 18, 21, or 12