Venita is factoring the expression 32ab-8b . she determines the gcf and writes the factored expression as . which best describes venita’s error? plz

Let's go through the steps of factoring that Venita should take.

1.) Find the greatest common factor (GCF). We only have two terms, so that makes it pretty easy.
32 = 1, 2, 4, 8, 16, 32
8 = 1, 2, 4, 8
The greatest common factor of 32 and 8 is 8. We can also factor out a b since that term appears in each part of the original expression. The GCF and variable should go on the outside of the parentheses.
8b(       )

2.) Now let's figure out what should go in the middle of the parentheses. To do this, use the original expression and divide each term. This is written in the parentheses. 

32ab ÷ 8b = 4a
8b ÷ 8b = 1

This would then result in the factored expression 8b(4a - 1). You can always check this by using the distributive property. Distribute 8b out to both expressions: 
8b x 4a = 32ab 
8b x 1 = 8b
32ab - 8b is the expression she started with, so your factored expression works!

Now that we went through the steps to solve the factored expression, let's check her answer. The only difference between Venita's and ours is that she has 0 as the second term while we have a 1. It seems that she had subtracted the GCF from the second term instead of dividing.