Answer: y - x = 1
Step-by-step explanation: Note : for two lines to be parallel, then they have the same slope.
i.e the slope is 1
Using y - y1 = m ( x-x1) to find the equation of the line
⇒ y - 2 = 1 (x - 1)
y - 2 = x - 1
y - x = -1 +2
y - x = 1
it could also be written in slope intercept form as y = x + 1
