There are some students in the two examination halls A and B. To make the number of students equal in each hall, 10 students are sent from A to B but, if 20 students are sent from B to A, the number of students in A becomes double the number of students in B, then find the number of students in the both halls.


Let the number of students in halls A and B are x and y, respectively.

Now, by given condition, x – 10 = y + 10


x - y = 20 …(i)


and (x + 20) = 2(y - 20)


x–2y = -60 …(ii)


On subtracting Eq. (ii) from Eq. (i), we get


(x - y) - (x -2y) = 80


y = 80


On putting y = 80 in Eq. (i), we get


x – 80 = 20


so, x = 100


Hence, 100 students are in hall A and 80 students are in hall B.


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