1. Are the following expressions equal ? Why/why not ?

i) x or y and not z 
ii) (x or y) and (not z)
iii) (x or (y and (not z)))

(i) and (ii) are same because in both these expressions first 'not', then 'and', then 'or' is evaluated. (iii) is different from both of them because 'not' and 'or' are evaluated first, then 'and' is evaluated