The best thing to do here is to put each of these into fractions, with the total (31) as the denominator.
14/31= silver
6/31= black
8/31= copper
3/31= various colours.
As you're looking for the keys that are silver or copper, you've got to add the two denominators together, which gives you 14+8= 22.
This cannot be simplified further, therefore, the probability of choosing either a silver or copper key is 22/31
Hope this helps :)
