(Q4).Solve each pair of equations by using the substitution method.

2x + 3y = 9

3x + 4y = 5

Given: 2x + 3y – 9 …….. (1)

3x + 4y = 5 ……. (2)

From equation (1);

2x = – y

x =
-y
Substituting x =
-y
 in equation (2)

we get

3 (
-y
 ) + 4y = 5
⇒
- y + × 4y
 = 5

⇒ - y + y = 5 ×

⇒ -y = -

y = +

Substituting y = + in equation (1) we get

2x + 3 (+ ) = 9

⇒ 2x = 9 –

⇒ 2x = -

⇒ x = -

∴ The solution is (-, )