Some billing questions regarding AWS Lightsail service.

**Condition one: ** So let's assume I created two $5/month aws lightsail instance on 5/1. I will only be able to use them for free for around 15 days, right? Because the free plan only contains 750 hours per month. Moreover, at the end of May, which is 5/30, I used 4T traffic on those two instances. Under such circumstances, how much will I be billed for May (only this single month) ?

**Condition two: ** So let's assume I create two $5/month aws lightsail instance at the middle of May, which is around 5/15. I used 4T traffic on those two instances during 15 days, how will I be billed at the end of May?

Thank you!