Question

A metal element (M) forms a hexadentate complex with the ligand ethylenediammine (en). Its formula is M(en)32+. The metal ion and the ligand do not absorb in the visible region of spectrophotometer and a 1.00 cm cuvette, the following absorbances were measured for various concentrations of the metal and the ligand:
[M2+] M---------[en] M-----------Absorbance at 450 nm
1.0 x 10-5------1.0 x 10-5------------0.03
2.0 x 10-5------4.0 x 10-5------------0.12
3.0 x 10-5------9.0 x 10-5------------ 0.27
4.0 x 10-5------6.0 x 10-5------------ 0.18
5.0 x 10-5------10.0 x 10-5---------- 0.30
6.0 x 10-5------18.0 x 10-5---------- 0.54
7.0 x 10-5------25.0 x 10-5---------- 0.63
8.0 x 10-5------20.0 x 10-5---------- 0.60

a.) Calculate the absorbance (same as extinction) coefficient for the complex at 450 nm
b.) What would be the absorbance of a solution with [M2+] = 2.5 x 10-5 M and [en] = 7.0 x 10-5 M ?
Please Help.thank you