Answer:
u should better search the google or this site www.edkasa.edu.pk u will defiantly find the answer.
Since two people take both courses, we can subtract two from 7, 8, and 21, giving us 5, 6, and 19.
Add 5 and 6 together to get 11. Since eleven students are in those two groups, we can answer this. The answer will be 11/19.
14(5)/15(7)
70/105
14/21
2/3