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 \( \mathrm{B} \) to \( \mathrm{A} \), the number of students in \( \mathrm{A} \) becomes double the number of students in B. Find the number of students in the two halls.
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 \( \mathrm{B} \) to \( \mathrm{A} \), the number of students in \( \mathrm{A} \) becomes double the number of students in B.
To do:
We have to find the number of students in the two halls.
Solution:
Let the number of students in hall A and the number of students in hall B be $x$ and $y$ respectively.
If 10 candidates are sent from A to B, the number of students in each hall is same.
This implies,
$x-10=y+10$
$x=y+10+10$
$x=y+20$.....(i)
If 20 candidates are sent from B to A, the number of students in A is double the number of students in B.
$x + 20 = 2(y-20)$
$x + 20 = 2y-40$
$y+20+20=2y-40$ (From (i))
$2y-y=40+40$
$y=80$
Substituting $y=80$ in equation (i), we get,
$x=80+20$
$x=100$
Therefore, the number of students in hall A is 100 and the number of students in hall B is 80.