Again to reiterate:
Image_X, Image_Y = Image location in WORLD space.
Screen_X, Screen_Y = Screen location in WORLD space.
Ship_X, ShipY = Ship location in SCREEN space.
During each loop:
To scroll background left: Screen_X = Screen_X - 10
Draw background Image at: Image_X-Screen_X, ImageY-Screen_Y.
Draw Ship at: Ship_X, Ship_Y
If you want the ship to move back when the screen scrolls left, then instead draw it at Ship_X-Screen_X, Ship_Y-Screen_Y. But remember that you will have to move it to the right at the same speed as the screen is scrolling left if you want to keep it on the screen.
Image_X, Image_Y = Image location in WORLD space.
Screen_X, Screen_Y = Screen location in WORLD space.
Ship_X, ShipY = Ship location in SCREEN space.
During each loop:
To scroll background left: Screen_X = Screen_X - 10
Draw background Image at: Image_X-Screen_X, ImageY-Screen_Y.
Draw Ship at: Ship_X, Ship_Y
If you want the ship to move back when the screen scrolls left, then instead draw it at Ship_X-Screen_X, Ship_Y-Screen_Y. But remember that you will have to move it to the right at the same speed as the screen is scrolling left if you want to keep it on the screen.