21 students because if 6 represents 30% u add 6 two more time which equals 18 and 90% then u add 3 more because it is half of 6. when u add 3 more u will get 21 and 100%
2nd, 4th, and 5th answers are correct
2.23606797749979
or round it to 2.2
1. x= 3/Y as a fraction btw
2. Same thing
