Solve the all parts of given problem:
Problem: The 633 nm from a helium-neon laser is shone normally on a plane containing two slits. The first interference maximum is 83 cm from the central maximum on a screen 12 m away.
Part I: Find the separation of the slits.
part II: How many interference maxima can be observed?
I want help to determine how many interference maxima can be observed.