If ~$a$~= 1+~$\frac{1}{4}$~+~$\frac{1}{16}$~ +~$\frac{1}{64}$~and ~$b$~=1+~$\frac{1}{4}$~a then what is the value of ~$a$~– ~$b$~?

-~$\frac{85}{256}$~

-~$\frac{1}{256}$~

-~$\frac{1}{4}$~

~$\frac{125}{256}$~

~$\frac{169}{256}$~