a$)$ "The values taken by the variables are left blank in the Karnaugh map below. Determine the variable values so that the reduced sum$-$of$-$products expression of the Karnaugh map becomes $f=\frac{*}{b}ar(c).$

$\backslash$table$[[abd,10,.,-$:$,.],[10,0,0,0,0],[-,0,1,1,0],[.,0,1,1,0],[.,0,0,0,0]]$

b$)$ "Using the specialized Karnaugh map you created, reduce the function $f=*b\frac{*}{b}ar(c)+*b.\frac{?}{\text{b}\text{a}\text{r}}(c)+*b*c+a*b*d.$

c$)$ "Reduce the same function using a standard Karnaugh map."