There are two classrooms A and B.If 10 students are sent from A to B, the number of students in each room becomes the same. If 20 students are sent from B to A, the number of students in A becomes double the number of students in B. Find the number of students in each room.
(3 Marks)

There are two classroom A and B.
if 10 students are sent from A to B, the number of students in each room become the same.
if 20 students are sent from B to A, the number of students in A becomes double the number of students in B.
Find the number of students in each room .
:
Let a = original no. of students in A
Let b = original no. of students in B
:
Write an equation for each statement, put eq in standard form:
There are two classroom A and B. If 10 students are sent from A to B, the number of students in each room become the same ."
a - 10 = b + 10
a - b = 10 + 10
a - b = 20 (1 Mark)

"If 20 students are sent from B to A, the number of students in A becomes double the number of students in B
a + 20 = 2(b-20)

a+ 20 = 2b - 40
a - 2b = -40 - 20
a - 2b = -60 (1 Mark)
Subtract the above equation from the 1st equation
a - b = 20
a - 2b = -60
--------------subtracting eliminates a, find b
b = 80 students in B
and
a - 80 = 20
a = 20 + 80 (1 Mark)
a = 100 students in A