From the introduction, each mask cost a different amount to purchase.
By clue 6, the four masks cost a total of $160.00, with the most expensive
selling for $64.00. Neither the Gollum (clue 2) nor the Pennywise (4) mask
sold for the high of $64.00. If the Freddy Krueger mask had cost $64.00,
by clue 3, Alex would have spent $32.00by clue 5, the least any mask would
have cost. Then the two masks together would have cost $96.00, leaving a
total of $64.00 to be spent on the other two (6). However, since no two masks
cost the same, one of the remaining masks would have had to sell for
more than $32.00 and the other for less. So, if the Freddy Krueger mask
were the most expensive, Alex couldn't have spent the least, contradicting
clue 5. The Leatherface mask cost $64.00 to buy. The Leatherface mask
isn't Luke's (1) or Alex's (5) choice. If Sean had bought the Leatherface
mask for $64.00, the Pennywise mask would have cost $48.00 (4). Then
the remaining $48.00 would have been split $40.00 on the Freddy Krueger
mask and $8.00 on Alex's choice (3). However, given amounts spent of
$64.00, $48.00, $40.00, and $8.00, there would be no way for clue 2 to work.
Therefore, Chris bought the Leatherface mask for $64.00. The Gollum mask
cost $32.00 (2). By clue 3, Alex didn't pick the Freddy Krueger mask; nor
did he buy the Gollum mask, or the Freddy Krueger mask also would have
sold for $64.00. Alex chose to go as Pennywise on Halloween. Since the
Freddy Krueger mask and Alex's pick cost $64.00 between them (6), by clue 3,
the Freddy Krueger mask cost $48.00 and the Pennywise mask $16.00. Sean
picked the Gollum mask (4). Luke chose the Freddy Krueger mask. In sum,
the four masks were purchased by the boys as follows:
 Chris, Leatherface, $64.00
 Luke, Freddy Krueger, $48.00
 Sean, Gollum, $32.00
 Alex, Pennywise, $16.00


