9 Two lms are shown on screen A and screen B at a cinema each evening. The numbers of people viewing the lms on 12 consecutive evenings are shown in the back-to-back stem-and-leaf diagram. Key: 1|6|4 represents 61 viewers for A and 64 viewers for B A second stem-andleaf diagram (with rows of the same width as the previous diagram) is drawn showing the total number of people viewing lms at the cinema on each of these 12 evenings. Find the least and greatest possible number of rows that this second diagram could have. On the evening when 30 people viewed lms on screen A. there could have been as few as 37 or as many as 79 people viewing lms on screen B