For each problem use boolean algebra to simplify the equation. SHOW YOUR WORK, one step per line. You should use only variable names, negation (with `!`), AND (by putting terms next to each other), OR (with `+`), and parentheses. In addition, each line should start with an equal sign (`=`). The first step has been done for you to show how. As a hint, problem 1c requires De Morgan's Law. 

Example) f(Z,Y,X) = !ZY!X + ZY!X + !YX

= (!Z + Z)Y!X + !YX = Y!X + !YX 

1a) f(A,B,C) = !A!BC + A!B!C + !ABC + !AB!C + A!BC 1b) f(A,B,C,D) = (A!D + !AC)(!B(C + BD)) 1c) f(A, B, C) = !(!(A + B)C)