light reflected from air wedge formed by glass plates.

I am having a bit of trouble with a problem in a algebra based physics course. Any help would be appreciated. Here goes:

When blue light (wavelength 589nm)is reflected from an air wedge formed by two flat glass plates, the bright fringes are 0.6cm apart.

1)How thick is the air wedge 5.0cm from the line of contact of the plates? (the wedge is viewed at normal incidence)

2) repeat for the wedge filled with oil (index of refraction is 1.4) instead of air.