Answer: play the six-trey, keep the nickel
Puzzle
Play the six-trey. Keep the trey-deuce.
Threes are trump, and the double is the top of that suit. West already led it. Your six-trey does not beat a double. Your trey-deuce does not beat it either. You are last, so nobody is coming behind you to save a mistake. The trick is theirs either way. It is one point if you play the six-trey. It is six points if you lay the nickel on it: one for the trick, five for the trey-deuce.
A lot of folks feel the higher trey in their hand and want to "cover." Covering does not matter once the double is out. The only choice left is whether the count goes with the trick.
West bid 30. They still have a ways to go. Do not start them off with a nickel you could have kept in your hand.
This answers an earlier puzzle. Don't feed them the nickel