SSC Steno Grade C and D 24 Dec 2020 Shift 1 Paper

In a class of 170 students, 155 students take part in either one or more than one class of either guitar, drum or violin. A total of 21 students take part in any two of the classes. 54 students take part only in drum classes, whereas 43 students take part in violin class only. Only 5 students take part in all the three classes. How many students take part only in guitar classes?