In a double-slit experiment, the slit separation is 1 mm, an…

In a double-slit experiment, the slit separation is 1 mm, and two wavelengths, 750 nm and 900 nm, illuminate the slits.  A screen is placed 3 m from the slits. At what distance from the central maximum on the screen will a bright fringe from one pattern first coincide with a bright fringe from the other?