Two narrow slits with a center-to-center distance of 0.48 mm are illuminated with coherent light at normal

Question:

Two narrow slits with a center-to-center distance of 0.48 mm are illuminated with coherent light at normal incidence. The intensity of the light falling on a screen 5.0 m away is shown in the figure, where x is the distance from the central maximum on the screen.
(a) What would be the intensity of the light falling on the screen if only one slit were open?
(b) Find the wavelength of the light.