Rearranging x+y-xr solve for y

The value of y = x (r - 1)

Given expression is : x+y-xr

Now, on rearranging the terms of the expression we get,

x - xr + y

Now, we put it equal to zero to find the value:

x - xr + y = 0

⇒ y = xr - x (The signs changes on moving from left-hand side of the equation to the right hand side)

⇒ y = x (r - 1)