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

Solution

Correct Answer: Option C

 

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

Then, x - 10 = y + 10     

Or, x - y = 20 .... (i)

And, x + 20 = 2(y - 20)

Or, x - 2y = -60 .... (ii)

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

So, The required answer A = 100.

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