3 sorry if it is wrong but have a good day
Answer:
1= 70
2= 65
3= 95
For 1, just solve 180-(65+45) and then for 2, subtract #1 and 45 from 180. Then just solve for #3 by using 180-(#2+20)
Answer:
The fraction of the students who failed to went partying = 
Step-by-step explanation:
Let total number of students = 100
No. of students partied are twice the no. of students who not partied.
⇒ No. of students partied = 2 × the no. of students who are not partied
No. of students partied before the exam = 20 % of total students
⇒ No. of students partied before the exam =
× 100
⇒ No. of students partied before the exam = 20
No. of students who not partied before the exam = 
Thus the fraction of the students who failed to went partying = 
First it can be a 2,4,6,8. Four numbers.
Then one is removed, leaving three numbers.
Then one is removed, leaving two numbers.
Possibilities for that to happen: 4*3*2 = 24.
Total amount of possibilities: 9*8*7 = 504.
So the answer is A: 24 out of 504.