The box with two silver coins is eliminated from the equation.
You have 3 gold coins in two boxes.
1 G coin in box A
2 G coins in box B
You pick a G coin... what are the odds that it is one of the ones in box B?
Look at the picture below. The columns are equivalent to the boxes. The one on the left is eliminated since you picked a gold coin.
https://i.imgur.com/03I9aL2.png
Edited by JeffB at 13:29:57 on 10/02/17