There are two class rooms A and B. If 10 students are sent from A to B , the no. of students in each room is the same. If 20 candidate are sent from B to A , the no of students in A is double the no. of students in B. then the no. of students in each room is ________

Question

$(A) \;A=100;B=80 \\(B)\;A=80;B=100 \\(C)\; C=90;B=90 \\(D)\;A=70;B=110$