How do i do this and the explanation

Answer: 2/5
Step-by-step explanation:
There are 12 window seats and 8 aisle seats:
The total number of seats would be 20, because you would need to add up the total number of seats.
12+8=20
The question is asking what the chance that the next seat will be an aisle seat and we know that there is eight aisle seats, therefore it would be 8/20.
However, this can be simplified down to 2/5. To get 2/5 you need to remember what the biggest number is that you can take out from 8 and 20, which is 4.
8/4=2
20/4=5
Therefore, 2/5 is your answer.