What is the purpose of the three part circuit?
@Neil_uk is right calling it a poor question.
The first part of the circuit attenuates the input signal to bring it within the range of the op-amp and whatever its output goes to.
The second part of the circuit is the op-amp itself. It's there to spare the designer the effort involved in applying Ohm's Law when there are several circuit elements involved. It's sometimes called an arithmetic-sparing op-amp: if it wasn't there the designer would have had to sharpen up his grade-school skills.
The third part is the RC low-pass.
You probably shouldn't be candid in answering the questions: think diplomatic. You don't want to offend the preparer of the question.
Follow-on thoughts: my &quot;arithmetic sparing&quot; characterization is what I think when I see similar circuits (very often). There are situations where the optimal design might very well be done this way. The questions you posed were given you to help prepare for your final, if I understand you. Your final won't have essay questions. Your questions must just be pointers to the types of analyses you should be able to handle in answering questions that might actually be on the final. Good luck on that final.