Question

There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is:

• A. 20
• B. 80
• C. 100
• D. 200

Answer 1

The correct option is C

100

Let the number of students in rooms A and B be x and y respectively.

Then, $x-10=y+10\Rightarrow x-y=20$ ...(i)
and $x+20=2(y-20)\Rightarrow x-2y=-60$...(ii)

Solving (i) and (ii) we get: x=100, y=80.

$\therefore$ The required answer A =100.