Question

The y-intercept of the line whose equation is x - y = 7 is

Answer 1

x- y = 7
⇒ y -x = -7 (multiply by -1 on both sides).
⇒ y +(x-x)= -7 +x
⇒ y= x-7

The y-intercept of the line is y= x-7.

Hope this helps~

Answer 2

x-y=7
 so you have to rewrite the equation in the form of mx+b=y
so ... x-y=7 
         -x     -x
     -y=7-x then simplify
-y(-y)=-(7-x) multiply both sides by -1
y=-7+x
  which is the same y= x-7
                                y=x+-7