Draw the graph of each of the following linear equations in two variables: 

(i) x + y = 4 

(ii) x – y = 2 

(iii) y = 3x 

(iv) 3 = 2x + y

(i) x + y = 4 

⇒ y = 4 – x

For x =  0,  y = 4 – 0 = 4

For x = 1,  y = 4 – 1 = 3

For x = 2,  y = 4 – 2 = 2

We have the following table with all the obtained solutions:

On plotting the points (0, 4), (1,3) and (2,2) on the graph paper and joining them, we get a straight line AB.