A survey of 39 university students found: • 10 worked part-time while studying • 18 received financial help from home • 19 withdrew money from their savings as needed • 2 financed themselves from all three sources • 12 received financial help from home only • 5 received financial help from home and withdrew money from savings • 6 financed themselves only by working part-time and withdrawing money from savings. Determine how many students: a did not finance themselves using any of the three resources