Answer: 6
Explanation:
So, he wears the shirt 10 out of 20 days.
10 days is half of 20 days.
This means he wears the shirt approximately half of the time, by the logic of 10/20 days.
So, now we apply this to 12 days.
What's half of 12? 6.
This means that he most likely wears the green shirt on 6 out of the 12 days.