15 In a survey, some people were asked which of three songs, labelled A, B and C, they liked best. The diagram shows part of a pie chart illustrating the results. The angle of the sector that represents the people who liked C best is 168°. (a) Complete the pie chart. (b) Expressing your answer in its lowest terms, find the fraction of people in the survey who liked C best. (c) Given that 30 people liked A best, calculate the number of people in the survey.