Chemistry problem

I have tried to play with all the numbers in this question but nothing seems to be working.

Nitrite ion, NO-2 is used as a preservative for bacon and other foods.  It has been the center of controversy it is potentially carcinogenic.  

Here is an abbreviated procedure for the determination:

Step 1: To 50.0 mL of unknown solution containing nitrite is added to 1.00 mL of sulfanic acid solution
Step 2: After 10 min, 2.00 ml of 1-aminonaphthalene solution and 1.00 mL of buffer are added
Step 3: After 15 min, the absorbance is read at 520 nm in a 5.00 cm cell

The following solutions are analyzed:
A. 50.0 ml of food extract known to contain no nitrite (i.e a negligible amount); final absorbance =0.153
B 50.0 ml of food extract suspected of containing nitrite; final absorbance =0.622
C. Same as B, but with 10.0 mL of 7.50 x 10^-3 M NaNO2 added to the 50.0 ml sample; final absorbance =0.967

a) Calculate the molar absorptivity, of the colored product.  Remember that the cell is 5.00 cm cell was used
b) How many micrograms of NO-2 were present in 50.0 ml of food extract.