First of all, Salome, please, watch your tone. We've talked about it earlier as you remember and I already don't like it.

Second of all, didn't you know this morning that you were not coming to school? Couldn't you text me that you were unable to come if you've been sick since Friday? Why is this such a problem to let your teacher know in advance that you're missing such an 'important' presentation?
Ignoring all this, finding excuses for yourself because you were sick but never letting me know about this, you just didn't come to your presentation and still call me unfair. Do you really think it's appropriate?

Your presentation is your responsibility, not mine.
Knowing the details of the presentation that I gave is also your responsibility, not mine. If you're too busy doing something else on your laptop during my class, you shouldn't be angry with me for not knowing how presentations are conducted.
Not letting me know you were missing the presentation is your responsibility, not mine.

If you considered this presentation so important you could've tried to avoid this situation. Do you understand that today two pairs had to present? And you expected that I would just have to postpone all the dates only because you missed your presentation without directly contacting me? Or is it fair to expect me to stay after class just because you didn't want to take 2 minutes of your time and text me that you were not coming for your presentation?