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:  Select:
A) 100 B) 110 C) 120 D) 130 E) 140
Let the number of students in rooms A and B be x and y respectively.   Then, x - 10 = y + 10 x - y = 20 .... (i)   and x + 20 = 2(y - 20) x - 2y = -60 .... (ii)   Solving (i) and (ii) we get: x = 100 , y = 80.   The required answer 100 = 100.
<result>A</result>
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: