Monochromatic electromagnetic radiation with wavelength A from a distant source passes through a slit. The diffraction pattern

Question:

Monochromatic electromagnetic radiation with wavelength A from a distant source passes through a slit. The diffraction pattern is observed on a screen 2.50 m from the slit. If the width of the central maximum is 6.00 mm, what is the slit width a if the wavelength is
(a) 500 nm (visible light);
(b) 50.0µm (infrared radiation);
(c) 0.500 nm (x rays)?