Please check my math/logic.
I hold the Q of suit when the board (at the river) shows 4 others of that suit. What are the chances someone holds the A or K of suit? The board is unpaired so I don’t need to worry about a boat.

I think it is calculated as:
16 places the A could be in opponents hands(9 handed game) and 45 unseen cards. So 16/45 = .35 or 35.5%

Same for the K, 35.5%

Is it proper just to add those two and say there is a 71% chance someone holds either the A or the K?