Someone calculate 4 months with 16%. Tell me how much time is left to do?

Do you mean 21 days left. Not 21 months left.

My man locked up. They gave him 16 months and he did 7 months in county. He hAs to do 4 months up state and that's where he at right now. The prison he is at they do 16% of there time. What's 4 months with 16%. This is what I got 120 days is 4 months. So I multiple 120*16 gave me 20 days that he has left to do. I'm not good at math so I ask someone else. So what I did you think that's correct