Answer:
do you have to add the numbers together or multiply
Solution:
The given equation is

Now we will factor the middle term as per the ac-method because the given equation is a quadratic equation.

The total number of keys equals:
12 + 5 + 11 + 2 = 30 keys
The probability to pick a sliver key is:
12/30 = 2/5
The probability to pick a copper key is:
11/30
Hope that helps