Question

Ifx+y-1=1-(1-x), what is the value of y?.

Answer 1

If you distribute the negative sign on the right hand side, you have

$x+y-1=1-(1-x) \iff x+y-1=1-1+x \iff x+y-1=x$

You can simplify $x$ from both sides:

$y-1=0$

And if you add 1 to both sides, you have

$y=1$