in a coaching centre of 70 but 4 students went on a university visit.31 went to unilag,35 went to lasu and 36 went to u.i. 10 went to all the three universities, 12 went to unilag only, 13 also went to lasu only, 15 went to u.i only. how many students visited
1 . . unilag and lasu
2 . .at...