The best statement that describes Simone's error is:
Simone did not use the greatest common factor in the equation.
The greatest common factor (GCF) of 24 and 56 is 8, which she correctly identified, but her breakdown into the expression \( 8(4+7) \) is incorrect because 4 and 7 do not relate to the original numbers in a way that makes the equation equivalent. The correct equivalence should reflect the sum \( 24 + 56 \) through the GCF properly.