Help for a question

[Cujo]

I'm having trouble to answer all the questions. So I would love some worked help thanks 

[Nusa]

You need to know the rules you are being tested on to know the answers, but don't forget the "graphically show" part of the question.

[rstofer]

What you need to do is use a fine tip pencil to draw vertical 'cursors' at the 4 points where the waveform crosses 1V (10%) and 9V (90%).  Take the left two cursors (10 and 90%) and measure the time between them.  This is 'rise time'.  Take the right two cursors and measure the time between them.  This is the fall time.

The definition of 'pulse width' varies, read your book. One definition would be to take the time between two cursors at Vcc/2 or 5V.  So, draw two more cursors and measure the time between them.

Page 8 here: https://www.ti.com/lit/ds/symlink/sn74ls04.pdf  There are a lot of examples that are working on Vcc = 3V.