y – 4 = 0 is the equation of a line

y – 4 = 0

⇒ y = 0 + 4

⇒ y = 0

Therefore, the value of y co – ordinate will be 4. Hence, the line will pass through (0,4) .

Since, the value of therefore, it will pass through all values of x while y will remain constant. Hence, the line will be parallel to x-axis.