a. Let P = ($.01, $.02, ... , $l.OO, $l.Ol, ... ) represent a set of possible prices for a given commodity, and let 0 = [a, (0) represent possible levels of quantity demanded. Define S: P ~ 0 as S = ((p, q): q = 20p-1S, (p, q) E P x 0).

h. Let A = (V: D = {(XI,X2): XI E [al,bd,x2 E

[a2' b2ll, al < bl, a2 < b2) be a set of rectangular sets. Define S: A ~ R as S={(D,y): y= areaofD,(D,Y)EAxR+).