Solve the following pair of linear equations by the substitution method.

3x - y = 3 and 9x - 3y = 9

Given,

3x - y = 3 ………(1)

9x - 3y = 9 ……..(2)

Solving equation (1),

⇒ 3x - y = 3

⇒ y = 3x - 3

Solving equation (2),

⇒ 9x - 3y = 9

⇒ 3(3x - y) = 9

⇒ 3x - y = 3

⇒ y = 3x - 3

We get, y = 3x - 3 by solving both equation (1) and (2).

Hence, y = 3x - 3, where x can take any value, i.e., infinitely many solutions.