A Fire Safety Officer examined 120 schools, looking for faults in fire exit signs, fire extinguishers and fire alarm systems. He found 18 schools without proper fire exit signs, 24 schools with insufficient fire extinguishers and 15 schools with faulty fire alarm systems. 5 schools had exactly two faults, 4 schools had all the three faults, only one school had faults in fire extinguishers and the fire alarm system, and 8 schools had faults in the fire alarm systems only. Draw a clearly labelled Venn diagram to illustrate the given information. Hence, find the number of schools (a) without any of the three faults; (b) who had only insufficient fire extinguishers; (c) without proper fire exit signs only.