x -y  = -3 what is this in standard form

There are a few different standard forms for a line, let's assume we're after

Let's write

That's already in standard form and we could stop. Or we could multiply by 10.

We can bring the constant to the same side; some people prefer that as standard form:

There's also slope intercept form,

Plenty more forms where these comes from.

just get this app called photo math it should be able to do those