The page margin is slanted

If the page margin is slanted, check that the correct size paper is being used, and also check that it is positioned exactly along the right side of the paper tray edge guide.

Seting the paper properly against the edge guide

Next, check the paper size and margin settings in the page layout settings menu of the application.

You should also make sure that the correct paper size has been selected in the printer driver.

The paper size is set in the printer driver's Paper dialog box in Windows or in the Print dialog box on the Macintosh.

The Paper menu in Windows