Here is the reply to your question.
To maintain your PR status you have to stay total of 2 years out of 5 years that is 730 out of 1825 days. You can add the number of days you stayed and I think as you have said 3 years and 6 months you have stayed in the 5 years then it means you are ok to keep you PR.
To maintain your PR status you have to stay total of 2 years out of 5 years that is 730 out of 1825 days. You can add the number of days you stayed and I think as you have said 3 years and 6 months you have stayed in the 5 years then it means you are ok to keep you PR.