Answer correct or incorrect
Let, Number of multiple choice = x
Number of short answer question = y
Now, x + y = 20
& 3x + 11y = 100
Multiply 1st equation by 3, and subtract from eq,2,
3x + 3y = 60
After subtraction,
8y = 40
y = 40/8
y = 5
Now, substitute in eq (1),
x + 5 = 20
x = 15
In short, There are 15 Multiple choice & 5 short answer questions
Hope this helps!
Im confused as to what you are asking!
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 = 