Question

Calculate the concentration of bromocresol green (BG) indicator

It says that Molar absorptivity = Absorbance at a wavelength/ concentration of BG indicator

I am having trouble calculating the concentration of BG.

Other info: Stock solution of BG = 80.0 mg/L and molar mass = 698.0 g/mol
We added 10.00 ml of stock solution to a 50.0 ml volumetric flask and diluted it to the line with 0.4M HCl

Answer 1

You don't have enough information posted to calculate concn.
First you need to calculate molar absorptivity, which as your post says is e = A/c (that comes from A = e*c)
If you used the diluted stock solution for that, you can calculate e by substituting the absorbance of the diluted stock solution.
Then you must have some other solution for which you want to calculate c, which can be done by A = e*c.
Post your additional information here if that is needed.