official SAT Test No13 Section 4 (Survey - Equation -manipulation problem- Interpretation Problem )

For a survey, students were assigned to either group R or group V, Combined the students in both groups answered a total of 17 questions. Of these, a
total of 9 questions were answered by the students in
group V, The equation 4r +9 = 17 describes this situation, where r represents the number of questions answered by each students in group R.
Which of the following is the best interpretation of 4r in this context