To solve this problem it is necessary to apply the related concepts to the principle of overlap, specifically to single slit diffraction experiment concept.
Mathematically this can be expressed as:

Where,
d = Width of the slit
Wavelength
Angle relative to the original direction of the light
m = Any integer which represent the order of the equation (number of repetition of the spectrum)
To solve the problem we need to rearrange the equation and find the wavelength

Our values are given as,



Replacing in our equation we have,




Therefore the wavelength is 523.2nm