The general equation of the line is ⇒⇒⇒ y = mx + c
where: m is the slope of the line , c is constant
given x+y = 6 ⇒⇒⇒ y = -x + 6
The slope of the given line = -1
The required line is parallel to the given line .
So, the slope of the required line = -1
∴ m = -1
The general equation will be ⇒⇒⇒ y = -x + c
The origin (0,0) point is on the required line
substitutes to find C
∴ 0 = 0 + c ⇒⇒⇒ c = 0
The equation of required line is ⇒⇒⇒ y = -x OR y + x = 0