Write in slope intercept form, then convert to standard form Slope=1, y-intercept=-3

Slope = 1

y-intercept = - 3, which can be expressed as (0,-3).

y - y_1 = m (x - x_1)

y - (-3) = 1 (x - 0)

y + 3 = x

The slope-intercept form is

y = x - 3.

The standard form is Ax + By = C.

y = x - 3

3 = x - y

Done.