<PRE><B>Question 388456</B>
GCF is the greatest common factor.
20a^3b, 32a^2b^2, and 12ab^3
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20a^3b=2*2*5*a*a*a*b
32a^2b=2*2*2*2*2*a*a*b
12ab^3=2*2*3*a*b*b*b
Now you need to find the common factors in each term.
2*2*a*b=4ab is common (contained) in each of these terms. 

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