Task: write on a pdf
Assumptions:
Write a pdf using acrobat mobile app.
Steps:
Install the acrobat mobile app in your phone
Open the acrobat app
Select file on the bottom menu bar
Open your pdf
Allow editing mode by selecting the big blue tools button in the lower right corner
Choose comment
Select the add text tool on the bottom toolbar
Type your text into the appropriate location on your pdf
Select the blue check mark button on the top menu bar to finish your work.