Answer has to have fractions

Q5. There are 180 students at a college following a general course in computing. Students on this course can choose to take up to three extra options. 112 take systems support, 70 take developing software, 81 take networking, 35 take developing software and systems support, 28 take networking and developing software, 40 take systems support and networking, 4 take all three extra options. (a) In the space below, draw a Venn diagram to represent this information. (4) A student from the course is chosen at random. Find the probability that this student takes (b) none of the three extra options, (c) networking only