Laser light with a wavelength = 665 nmnm illuminates a pair of slits at normal incidence.

What slit separation will produce first-order maxima at angles of 30 from the incident direction?

Express your answer in micrometers.

I would like an explanation on how to accurately find the correct solution to this question. So far, the answer that I got is not correct (1.33 micrometers) and i have frustrated myself at this point.