Y+1=x : write the equation in slope intercept form to find the slope and the y-intercept

We know that y=MX+c
here m=1 and c=-1

You have the equation:

Y + 1  =  X

You need it in "slope and intercept" form.
Slope and intercept form is:

Y = (slope) X + (intercept)

The equation you have ALMOST looks like the form you need,
but there's something wrong.   

What you have is:  Y + 1 = X .
What you need is ' Y ' on one side all by itself.

How can you get rid of that " + 1 " that's on the left side with Y ?

Well, you can subtract ' 1 ' from the left side of the equation.
But whatever you do to one side, you must do the same thing
to the other side.
No problem !  Take the original equation:

Y + 1  =  X

Subtract ' 1 ' from each side:

Y = X - 1

And there you have what you need.

Remember, "slope and intercept form" is

Y = (slope) X + (intercept) .

and you have 

Y = (1) X + (-1)

The slope is 1 .
The intercept is -1 .

You're letting something easy scare you and
grab you by the throat.  Don't let it do that.