A slit has a width of W1 = 2.3 10-6 m. When light with a wavelength

Question:

A slit has a width of W1 = 2.3 × 10-6 m. When light with a wavelength of λ1 = 510 nm passes through this slit, the width of the central bright fringe on a flat observation screen has a certain value. With the screen kept in the same place, this slit is replaced with a second slit (width W2), and a wavelength of λ2 = 740 nm is used. The width of the central bright fringe on the screen is observed to be unchanged. Find W2.