Not asking for answers necesarily but I would to know how to approach each question

Question

Mass of pure acetylsalicylic acid (ASA) : .508 g

Dilution Absorbance (a.u.)
2:11 .116
4:11 .259
6:11 .392
8:11 .502
10:11 .548

Mass of tablet : .380 g
Absorbance read on the Spec 20 : .314 a.u.
Concentration of the solution : 5.42e-4 M

Using reverse dilution, calculate the concentration of the tablet in the 100 mL diluted solution.

M

Calculate the number of moles in the 100 mL diluted solution.

moles

Calculate the mass (g) in the 100mL diluted solution.

g

Determine the mass of ASA in 250 mL.

g

Determine the % of ASA in the tablet.

Determine the number of grains of ASA.