Respuesta :

20 = 2*2*5
45= 3*3*5

5 is common  so the GCF is 5
What is the Gcf of 20,45x?

GCF mean greatest common factor.
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In order to find the greatest common factor is finding the factors of each number. Remember that factors are numbers which can be multiplied together to get a product, in this case, 45, and 20. 
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 20: 1,2,4,5,10,20 45: 1,3,5, 9, 15,45 
  So your GCF would be five.

Hope This Helps :)