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:	Choose the correct answer:
A) 20	B) 80	C) 100	D) 200	E) 120
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 A = 100.   ANSWER:100
<result>C</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: