Dude, if a teacher gave you this question, just tell him/her:
"yeah, we googled that math problem and the answer was -87, so it MUST be right"

=)

__________________
2009 Kia Sedona
2009 Honda Odyssey EX-L
12006 Jetta Pumpe Duse
(insert Mercedes here)

Husband, Father, sometimes friend =)