This is a very impressive site with so many clever people amongst you. I'm trying to understand the work my granddaughter is doing so I can discuss it with her and help, but this defeats me. I know it's probably simple, but could someone please explain it to me. It's the brackets that I don't understand in the NOT(A AND NOT B) Truth tables can be used to show whether or not two Boolean expressions are equivalent. By copying (please make sure you copy the first two columns exactly as shown) and completing the truth tables given in Figure 5 below, show that NOT A AND NOT B is not equivalent to NOT (A AND NOT B) Make sure you end your answer with a proper conclusion.