Question

Write the linear equation representing a line which is parallel to x axis and is at a distance of 4 units below x axis

Answer 1

x = 0
y + 4 = 0

hope it helps

Answer 2

suppose the equation of the line which is parallel to x axis is .. y=c
since it is 4 units below  the x axis , the line y=c passes through point (0,-4) 
then c=-4 

therefore the linear equation representing a line which is parallel to x axis and is at distance of 4 units below x axis is......- y = -4