So, this is pretty simple. First, we need to know that slope intercept form is y=mx+b, m equals slope and b equals y intercept. Thus, the equation will be y=1x-4. When you have a positive number as your y intercept then it would have a + after mx but, since we have a negative number here it will have a - after mx.
I hope this helped! Have a great day and reach out to me if you need any more help!