Hand written solution required

A double-slit interference experiment uses green light with a wavelength of 5000 A (1A = 10-10 m) and violet light with a 4000 A wavelength. When using green light where the gap between the slits is 'd', an interference pattern is formed on the screen, which is 'L' away from the double- slit. So that when using violet light, the distance of the first bright band from the central light is the same as when exposed to green light, what must be the distance between the slits and the screen