<PRE><B>Question 164257</B>
(-5a^-2b^2)(-3a^3b^-4)
=(-5b^2)(-3a^3)
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  (a^2)(b^4)



=15a^3b^2
 --------
   a^2b^4


=15a
 ---
  b^2


=15ab^-2</PRE>