Suppose the teacher begins recording on a digital camera with an hour available. show that there is enough time to record everyone if she gives a 15 minute introduction at the beginning of class and every student takes a minute to get ready.
much time is left on the digital camera?

22.Suppose that the teacher started recording on a digital camera with an hour available. She gives 15 minutes introduction. Thus 60 minutes – 15 minutes is 45 minutes. She still have 45 minutes remaining, now the question is how many minutes will remain if she uses 1 minutes per students. Since the number of students is not given. It depends on how many students will be there. For example 25 students thus that’s equals to 25 minutes also. So she has a 20 minutes remaining.,

You want to isolate your variable.