Rolling a 3: 1 out of 6
Rolling an even number: 3 out of 12
Just remember the sides of your dice.
1 2 3 4 5 6
The question is asking the probability of getting a 3. Well there is ONE 3 out of 6 numbers so 1 out of 6.
1 2 3 4 5 6
Now the second part is asking for an even number. There are THREE even numbers on a dice so it'll be 3 out of 6 but now this is the SECOND ROLL so it'll be 3 out of 12
1 2 3 4 5 6
I put the numbers to explain it a little better in bold, underlined and italicized.